Jon:
IMHO do a lot of research. The ZF in the Pantera must be inverted and while thats happening most guys opt to go thru the box and have it refreshed while it is apart, you will also need a new top cover with mounting lugs. By the time you get thru all that you could have a new box with limited slip, and have chosen gear ratios in the process.
A simple bellhousing with a stock Ford clutch and starter and you are basically done.
I am not against the other transaxles, and some of the Porsche units are seriously strong, but usually they require a smaller flywheel and clutch, adapter plate, and the starter mounts on the gearbox housing which in a lot of chassis is an interference point. The plus side is that when inverted they allow for the motor to mount relatively low in the chassis.
One drawback is that unless you get a short G50 or 930 trans they can also be too long for some chassis and interfere with the bodywork in the rear.
The Audi is a relatively inexpensive box, but runs in normal configuration which wont allow your motor to go as low as you may want to place it, but being inexpensive and easy to setup with a shifter makes for a good compromise, just get the right box with good gearing and it will give good service if you don't beat on it.
A new ZF will run you close to $10,000 all in, but I have seen guys spend close to that on some of the other boxes with all the adapters and custom stuff to get it to work.
The new Griffin seems very promising and seems like a good choice also, although I don't have experience with it, it looks to be purpose built for our type of application and probably will save you a lot of headaches on install and such.
Cheers
Phil
