I am buying a 700 R4 out of an 84 corvette and the torque converter is different,my tranny went on teh Iroc,no reverse or 4-5th gear ,so can I use my old Iroc one or do I need to buy a new one?

 

A few things...

The 1984 V8 700-R4 had a 27 spline converter (early ones. This interchanges with the 200-4R) and they also had 30 spline converters (late 84. This interchanges into the early 90s 4L60-E before the 4L60-E went to a pulse width modulated TCC.) My point? An 84 might have a converter that works for your 88 or 92. (Since you didn't reference your source for "it's different," I thought I'd mention all this.)

Secondly, the Vette 700-R4 case lacks a mount location behind the pan like the F-body cases have. There are a few ways around this. One is an aftermarket crossmember for the 1989 only Turbo TA that also has a torque arm mount. This works because you can put a Caprice tailhousing on which has a mount location that interchanges with the 200-4R in the 89 TTA, but lacks a mount for the torque arm.

Thirdly, the Y-body had independent rear suspension so the differential stays in one place. This means a shorter slip yoke can be used and in the case of the Vette 700-R4, it has a shorter output shaft. So, you need to be very careful to measure and double check the yoke to shaft depth mating. A longer yoke can be one way around this, but it's possible to get one too long.

So, tally up all those modifications to make it work. Then you have a non-standard (but probably nice shifting) used transmission. Sending yours to a reputable builder and ending up with a new trans. might be the better option.

Sorry about your T5.