Pre 1959 Panhead Transmission Gear Info Needed.

[Orion]

I also posted this under Panhead, but seen this topic forum it might get a quicker response. Im working on a early Panhead transmission pre 59 and the low-second gear cluster is missing. I have found many 59 up gears but not the pre 59. I have found out the pre 59 is a 15-20 tooth count as is the 59. So why wont the 59 fit? I got my info from J&P Cycles about tooth count, but they state the third gear would mesh up. Why wouldnt it if they are both the same tooth count?

[RUBONE]

See my reply in the other post!

[Orion]

I seen the post, but my main question is Why wont they interchange having the same tooth count?