I've been told that 1251/6b selector keys are unavailable? I've also heard that the 1251/5a keys are available? I have a 5a & a 6a motor, both these motors share the same selector key. Witch is shorter than the 6b key. Question is if I wanted to build a 6b motor and have a new selector key in it could I swap the whole 6a trans. into the 6b cases? Some may ask why? The 6b motor has less space below the piston and crank area resulting in higher compression and alegedly more horsepower. Any thoughts on this subject would be greatly appreciated. Keep the rubber side down.
Gavin
Check to see if your 5A and 6A engine have a two piece shifting lever. If so, the key should be the same as the 6B. If the 5A has the one piece shifting lever, it will have the smaller key. The main shafts are the big difference. The clutch side of a old main shaft requires a different size bearing than a new main shaft style so it won't interchange in some cases. Gear thickness is different on the 5 and 6 speed transmissions, as well as tranny spacers. Check your shop manual! There are large shift keys out there, you might try Al Buehner or query the POG. Good Luck!
I put a 1974 6B, 6 speed gearing into a 1971 5A engine, no problem. 6 speed gears are thinner, allowing the conversion. 1 and 6th are the same ratio, just one more step in getting there.
kc