Right.
The gearbox is essentially the same, so a TDi one will last for yonks because it doesn't get the same grief, BUT
The valving is all different, the gearchange points and kickdown are all differnet to suite the slower-running TDi, probably about 1,000rpm I'd say so you would end up blowing the TDi apart in short order.
The torque converter on the TDi is noticeably smaller and again has a different stall characterisitic, also when combined with the TDi flex-plate it has a differnet second moment of area (flywheel-ness).
The pedalboxs are essentially the same but the auto brake pedal is wider.
However, if the bellhousing fits a TDi, are you sure it wasn't already converted to a TDi engine? what's it's history.
The wiring loom you fitted may already have connections for the autobox, the starter inhibiter etc.
You'll need a new console, shifter and surround. The transfer box selector might be different. too..
Also, and I need to check this, but I think a TDi gearbox sits further forwards compared to a V8.
