Some of the gears from the 78 will have a line that's machined into the center of the teeth that runs all the way around the gear, so that's one way to identify them. Many of the other gears are the same between the two transmissions.

I posted some info on part numbers and ratio differences between the early K, later K, and F models a while back over on www.sohc4.net:

http://forums.sohc4.net/index.php?topic=61641.msg671917#msg671917

hth
myst1c

"Know the smallest things and the biggest things, the shallowest things and the deepest things."
- Miyamoto Musashi