does the 27 spline shaft hold up with all the torque? I'm really wanting to stay with the th350 at this point. Seems like moving up to the 400 would create a bunch more issues.
The 27 spline shaft will hold up just fine--especially if you only use hard street tires. The weakest link seems to be the outer sprag race. It sometimes brakes on a harsh 1-2 shift. A hardened race is a fix for some power levels. But, while spending $$ on it, I'd have the sprag/drum/race swapped out for either a 36 element sprag/drum/race assembly, or the spragless assembly.
Most of the HD trannys you see advertised, use the 36 element srag set-up. So, I have to assume these are considered by most, the best way to go.
Many sprag and race failures are said to be caused by valve body shift kits which cause harsh 1-2 shifts. Many say the Trans-Go shift kits are the best.
