Hello all... I am starting to brush up on my information to do a T56 swap in my TA. But I had a couple burning questions I was hoping someone could answer for me... What is the difference between the early LT1 T56s and the later years up thru 97? Is there a certain year I should be looking for? Is one geared better than the other? Is there even a difference between the two!? Any useful and conclusive info would be highly appreciated.

 

94-97. Avoid 93. It has the MUCH wider ratios. The later trans, plus 3.73 gears BARE MINIMUM, are the way to go.

 

So the 93s are "off limits"? Ok I think I can handle that. Any other tips I should be aware of?

 

No, not a whole lot.

Look at the sticky at the top of this forum, and the post in teh FAQ forum on this site. I don't think there's any possible way anything could come up that isn't addressed in at least one of those.

 

Thank you sir for your help. I will do that

 

As far as 1993 boxes...
An RPO M28 unit (GM 10236020 / TTC 1386-006) isn't ideal, ratio-wise, with 3.36 first / .62 sixth.

An RPO M29 unit (GM 10236021 / TTC 1386-007) is actually a good trans with regard to ratios of 2.97 first, .62 sixth and can be converted to .57 sixth.

Either one is weaker due to the lessened gear contact width at the maindrive to countershaft teeth.

I wouldn't hesitate to run an M29 unit, with the understanding that it'll never have ultimate strength, but for an average healthy 350, it's a great choice.

The MN6 units from 94-97 are largely the same internally (mild updates in '95) and have 2.66 / .50 ratios that work great if your rear gears match it well.