The GT40 was designed to use the ZF Transaxle.  Unfortunately these transaxles are getting rather scarce and the aftermarket is not bringing affordable alternatives to bear. 

The alternate transaxles recommended by the replica mfgr are:

1. *Audi 016 (which requires the engine to be mounted 1.5” higher in order to get an acceptable angle on the CV joints and half-shafts - not acceptable to me).
   

2. *Porsche 930 (long or short) - Pricey and only a 4 speed
   

3. *Porsche G50/01, G50/50 and G50/52 - Pricey and hard to find but they’re out there...
   

I’ve chosen to use the more common 1991 Porsche G50/03 and modify it to be acceptable to the Chassis.  This is a 5 speed transaxle that has been modified with steel synchronizers and oil spray ports to keep the gears cool (more on this in another section) 

There are modifications also required to make this transmission work in this replica:

1. *The Forward Mounting donut and boss must be removed
   

2. *The shifter-shaft must be shortened (this requires machining of the housing)
   

3. *Even shortened - the G50/03 is roughly 2” longer than the other G50 trans mentioned above so that means that the engine / transaxle needs to move forward. This is not necessarily a bad thing since the centerline of the transmission axle stubs are roughly 3” behind the centerline of the rear axles.