Reply to "GT5 Diff ratio"

There are two possibilities for your later Pantera Gt-5. First, does your transaxle differential case have a flat curved top that smoothly curves up to join the bellhousing, or is the diff case more cylindrical with small ribs? If its the former, you have a late model ZF, better known as the 'M-1' gearbox and virtually notjhing interchanges with the early unit. On the late box, the gears are heavier, the shafts thicker and the cases reinforced. The ratios are also different.
Second comment: there is a ZF Owners manual available that should be required to do more than change the gear lube in these expensive, complex transaxles. All the U.S vendors and Pantera Clubs sell them very reasonably. Finally, there are different ring & pinione ratios available as well as different 5th gear pairs, and only those sold by RBT Transmission are 'real' ZF parts. Long ago, the ZF factory in Germany sold the rights to the name, the internal specifications and all the tooling to RBT in Southern California. Other mfgrs gears may or may not hold up especially under the extra power yopu plan to build. To my knowlege, RBT only sells the gears if THEY personally install them, since its easy to screw up in this trans, especially with non-stock parts.