Not quite true about having to use the ZF transmission. The bolt pattern is different but it is only the one bolt at the 2 0'clock position ( facing the back of the motor). I think this bolt is different because there is a head bolt in the way. I have a T56 bolted up to a 94 LT5 and a friend has a C5 torque tube and T56 bolted up to a 90 LT5. It is true that the LS engined will be cheaper and parts are easier to find but to me they are pretty ugly compared to the LT5! Good luck with the project!

The ZF6 is a much beefier (and way more expensive) unit than the Borg Warner T56. Both the ZF6 and T56 have different max torque ratings based on what car they came out of since both saw duty behind many differnet engines in many differnt cars. C4 corvettes didn't have a trans crossmember, just an aluminum torque arm supporting the back of the trans. So the ZF6's found in C4's don't have provisions for a crossmember.

The torque arm mount is also completely different, it resembles the mounting surface found on the differentials of thirdgens. One more difference is the shifter location and style. It is set way back, biased toward the drivers side, and is a linkage style, not the conventional top loader of the T5 or T56.

One more thing to consider is servicability. Although the ZF6 is damn near bullet proof, if you do manage to break one, you are in big trouble. Parts are almost impossible to find, and if you do find them they are outragouslt expensive. Also, rebuilding one is almost impossible because you need an oven. The bearing races in the case and on the various shafts are such a tight fit that they need to be heated up to like 400 degrees Ferenheit for 30 minutes or so to remove them! Forget about it.