I use an Audi 01E with a Quaife ATB mated to my Coyote gen 1, gearbox is cheap and plentiful, never heard of one failing in a GT40 or similar. Best code is FRF or DQS, original fit to a 2.5 Tdi (low revving v6) has perfect ratios for a GT40. A six speed box but 1st is just for pulling out of your driveway. With P Zeros on a dry road it will break traction at 90mph in 3rd, I ran out of underpants at 155 on the Kemmel straight at Spa when I was only half way through 5th. Top tip, powder coat the casings when rebuilding as the gearbox is very visible and when left as standard looks quite ugly quite soon.