I have a '93 T56 mated to an LT1 in my '89 Camaro with 3.42 rear gears and 275/35/18 tires.

After I swapped from an a4, I discovered that 4 gear grinds. So it needs to be rebuilt. OK fine. When I bought this trans, I was under the impression that it was from a '95 car so it had the .74/.5 overdrive ratios. This is not the case. Since the trans is coming out for a rebuild and is going to be apart, can I swap the 6th gear to obtain the .5 overdrive vs the .63 overdrive I have currently?

Or would it simply be easier to replace the 5/6 countershaft and both 5th and 6th gears?

I like the other ratios that I have and mainly want to lower my rpms while on the highway for better gas mileage.

Looking for input. Thanks.

 

From what i heard from some sponsors the 93 gear set in general is weak and should be replaced with the later 94+ gears if you can afford it. Just some info i thought i would through in there while you have it apart.

 

The ratios are made mostly by the input and cluster countershaft, the 5/6/R shaft is just along for the ride. You can put in a later 5/6/R cluster and driven gears from a later model, but the ratio change will be small and not the exact jump you're looking for.

 

The 93 trans has a different tooth count on most of the gears. Also the OD measurement is different on a few of the gears. This means that no gears are interchangeable with the 94-02 gears. You can't just change 5th & 6th gear to get a better overdrive. You would have to chage EVERY gear to get the ratios you are wanting. At this point it would be way cheaper to just buy a 94-97 style tranny. I would recommend keeping everything the same. You could change the rearend gear to 3.23, but it will not really make a difference in gas mileage.
I am offering a $650 rebuild special right now. So, just let me know. Thanks