Well after a little hiatus and some time researching and sourcing parts, we are back at it. Took out the trans and clutch yesterday to make way for this new baby:
It's a Tex Racing (now G-Force) T101A 4 speed from a Nascar team. Can routinely pick these up with some race miles on them for about $1800-2200, but I found a gem with mostly fresh/new parts on craiglist for $1750 in the gear ratios I was looking for - very close to the M-21/M-22 ratios.
2.26 1st
1.54 2nd
1.29 3rd
1.1 4th
It's got dog rings so can't wait to do some clutchless shifting and left foot breaking on the road course.
One of the reasons I liked this conversion is that it's nearly the same case size as the Muncies I'd been using, and the only things we think are needed for the swap are a clutch disc change (10 spline to 26), a Turbo 400/1310 yoke, and some tunnel mods to make room for the heim shift rods and bulkier Hurst Super Shifter.
Also cleaned up the dirty exhaust system a bit. A $5 can of Rustoleum goes a long way.
