H-D additional original component identifying numbers


Description: Additional original component identifying numbers

Author: Speeding Big Twin
Date: Tue Nov 05, 2019 12:00 am
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Category: Articles/Miscellaneous Info

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Found on some H-D parts is an additional original component identifying number, aka security code, aka anti-theft number, aka supplemental number. Some believe the practice began in 1963 while at least one publication said 1961. Several others say the additional ID began with 1962 models and I agree.

In the beginning, when used for Big Twins, it was stamped on the frame, lower triple clamp and trans case and it consisted of one letter followed by either three or four numeric characters. The first letter used was A and it applied to a lot of 62 models but A was also used for some 63 models. Some bikes had the same letter on all three parts while others didn’t and I’ll come back to that later.

BT frames had additional ID for 62–69. And it may also be found on some, but not all, 1970 models even though they had a VIN. Below is a list of letters and the model years they may correspond to but there can be exceptions so the list should be used as a guide only. Apparently the letter I was skipped, perhaps to avoid confusion with the number 1.

1962: A
1963: A and B
1964: B, C and D
1965: C and D
1966: D, E and F
1967: E and F
1968: G, H and J
1969: J and K
1970: K

On BT frames the ID is normally (always?) on the left side of the steering head but sometimes the characters are hard to see. The Panhead frame below has A1+++ heading downhill but sometimes the ID pointed uphill. The area does not appear to have been machined flat although it often was. Notice two small indents above the ID. Further up the frame is forging number 47591-35. It’s also interesting to note this frame was made in April 1961.

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Next is another Panhead frame but this one has B (B7+++). Date code is 3 K indicating the frame was made in 1963 in November so it may have been used for a 64 model. (The letter I wasn’t skipped in frame date codes.)

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Sometimes an additional ID letter at first seems wrong for the type of frame—for example, this appears to be F (F3+++) but it’s on a Duo-Glide frame.

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However, the date code indicated it was made in Dec 66 and F was one of the additional ID letters for 66–67 so the frame may have been a replacement. Another unusual example was D on a 1969 model but perhaps it too was a replacement and the additional ID from the original frame was applied to the new one.

Next are letters for BT lower triple clamps and model years they may correspond to and for now I’m just staying with 1962–85. I haven’t researched all BT lower triple clamps for this period so if anyone wants to add photos of other types and the position of the ID numbers then please do so. Again there may be exceptions so the lists should be used as guides only. Apparently the letters I, O and Q were skipped.

1962: A
1963: A and B
1964: B, C and D
1965: C and D
1966: D, E, F and G
1967: D, E, F and G
1968: H, J, K and L
1969: J, K and L
1970: K, L and M
1971: M, N, P and R
1972: P, R, S, T and U
1973: U, V, W, Y and Z. And X?


As of 1974 models, double letters began to appear and they were usually followed by four numbers. I’m not sure what the second letter was for each year but I’ll post some double-letter examples below.

1974: A and another letter
1975: A and another letter
1976: A (or B or C) and another letter
1977: A (or B or C) and another letter
1978: B (or C) and another letter
1979: B (or D or F) and another letter
1980: B (or D or E or F) and another letter
1981: E and another letter
1982: F and another letter
1983: F and another letter
1984: F and another letter
1985: G and another letter

NB: it may also be that some, not all, 1979–1980 model BT lower triple clamps had only one letter.

On 62–68 BT lower triple clamps I’ve only seen the ID stamped outside the left fork stop. As indicated above the first letter used was A but this lower clamp looks like it has B (B9+++) so it may be a 63–64 model. Not the best picture but at least it shows the ID location. In this example the ID heads uphill but sometimes it runs downhill.

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For BT triple clamps the next location for additional ID was on top of the padlock plate and this one has K5+++.

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The plate was introduced with 1969 models but it’s unclear if the change in ID position occurred immediately (early-69). I haven’t seen any 69 Shovel lower clamps with ID outside the left fork stop but if anyone has then please let me know.

Next is U2+++ and apparently U indicates 72–73.

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Double letters AH (AH8+++) although upside down. This was said to be a 75 model which is consistent with the info above but A accompanied by another letter could also indicate 1974 and 1976–77.


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Also upside down is FN6+++.

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Narrow triple clamps: on this one the letter looks like P (P3+++) so it may be from a 71 or 72 FX Super Glide. ID points uphill on the R-H fork stop.

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Next is S3+++ and it too runs uphill. The bike is a 72 FX and S is one of five letters associated with that model year.

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The above narrow clamps having a single letter is consistent with the format also used on Electra Glide lower clamps at that time (71–72).

But while some bikes apparently first went to double letters as of 1974 models, Super Glide lower clamps I know of on a 75 and a 78 only have one letter. It’s on the R-H fork stop which seems to be the normal position. The ID runs downhill but that’s okay and the characters appear consistent with factory types. The 75 has H (H7+++) and the 78 has F (F1+++) but on other previous models those letters indicated 68 and 66–67 respectively.

Panhead trans cases had additional ID on the front for 62–65. For Shovel trans cases the ID was on the front for 66 through about mid/late-79 but from then through about 84/85 at least two more locations were used on the types of cases I’ve looked at thus far. In the single-letter period the letters I, O and Q seem to have been omitted. In the double-letter era, I and Q appear to have been skipped but a question remains regarding the letter O, and what type of character represented it, at certain times.

NB: as with the letters for frames and lower triple clamps, there may be exceptions to this list for trans case ID so it should be used as a guide only.

1962: A
1963: A and B
1964: B, C and D
1965: B, C and D
1966: C, D, E, F and G
1967: D and E
1968: E
1969: E and F
1970: F and G
1971: G and H
1972: H, J and K
1973: K and L
1974: L, M and N
1975: N, P and R
1976: R, T, U and V
1977: V, W and X
1978: Y and Z. And maybe AA for late-78.
1979: AA, BB, BC and BD. And BF?
1980: BF, BG, BH, BJ and BK
1981: BL and BM. And BN?
1982: BR?
1983: BT
1984: BV

There was also BX but the date code is unclear in the photo I have so I’m not sure if the case was 84 or 85.

On the front of BT trans cases the additional ID was stamped just below where the lid attaches. The earliest case I know of to have this form of ID was cast in Jan 1960 and it has the letter A but another case from that month has nothing. Same thing happened with two cases I know of cast in Oct that year. One case I know of cast in Aug 1960 has A but I used the Jan 1961 case below as an example because its ID letter is clearer.

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Next is J and apparently it was one of at least three letters used for 72 model BT trans cases.

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NB: I don’t know how the factory assigned the letters but if J was on a BT frame and/or lower triple clamp it would normally indicate about 68–69.

Next is R suggesting a 75–76 trans case but if that letter was on a BT lower triple clamp it would usually indicate about 71–72.

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Additional ID remained on the front through S, T, U, V, W, X, Y and Z. However, the thirteen Ys I’ve seen are all larger than their accompanying characters as per the next picture.


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On most occasions the ID runs downhill but sometimes it heads in the opposite direction—for example, Z0+++.


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The earliest double-letter combo I’ve seen on a Big Twin trans case is AA but this photo of BB (BB3+++) is better.


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Other combos used on the front include BC and BD.

Second position I’ve seen for additional ID is toward the rear, on the left side behind the lid. On this occasion the first letter is B and the second letter looks like F.

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Another combo found in that position is BG.

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But shortly thereafter the ID shifted to the back of the case and BH is the first I’ve seen there.

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BN7+++

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Other double-letter combos stamped low on the back of the case are BJ, BK, BL, BM, BR, BT, BV, BW and BX. Not always toward the left however and sometimes you’ll find the ID further to the right.

Although there can be exceptions I imagine on most occasions the additional ID on a BT trans case will be consistent with the casting number and/or date code underneath. Below is a list of casting numbers and corresponding ID letters. (Others may be added later.) Remember in the single-letter period the letters I, O and Q seem to have been omitted and in the double-letter era, I and Q appear to have been skipped but a question remains regarding the letter O, and what type of character represented it, at certain times.

Also some cases with casting numbers have no date codes and some date codes are on cases with no casting numbers which is why this list may seem a bit out of step with some of the above info.

A: 121 35
B: 121 35, 34703 64 and 34703 65
C–V: 34703 65
W: 34703 65 and 34703 77
X and Y: 34703 77
Z: 34703 77 and 34709 78
AA: 34709 78
BC and BD: 34709 79
BF–BN: 34709 80
BR: 34709 82
BT: 34707 82
BV and BX: 34707 82A

When looking for this type of additional ID I mostly concentrate on BTs so I haven’t accumulated much for Sportsters but AFAIK the letters for their 1962–69 frames are the same as, or at least similar to, those applying to BTs. But I don’t know if any 1970 Sportster frames had additional ID. Anybody know?

Some Sportster frames have ID on the left side and some have it on the R-H side. This one has A7+++ on the left.

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Next frame has K4+++ on the R-H side.

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The only examples I have of additional ID on Sportster lower triple clamps are on the padlock plates. AFAIK, the letters for Sportster lower clamps are the same as, or at least similar to, those applying to BTs. This one is L5+++.

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T5+++

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Double letters AL (AL++++) upside down.

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