Jeff,
Everything except the engine and drivetrain was manufactured by General Motors Holden (Australian subsidiary of GMC). It's a Holden Commodore (VL series). It's the only which was delivered with the Nissan RB series motors, both RB30E and RB30ET.
I choose the RB25DET as I was given the option of a crashed '97 R33 GTS-25T with 11,000kms. The RB25DET is also good for just under 500hp with just a head gasket change. The car weighes only 1200kg so more than sufficient. I also didn't want the hassle of having to modifiy the RB26DETT 4WD sump and to also ditch the gearbox. I was only prepared to buy a front cut so that I got everything complete with the engine, including wiring harness, ecu etc...
The beautiful thing is that the RB25DET with gearbox slides straight into the VL body with any modifications. Engine mounts all fit, ancillaries etc... Even the old Holden prop shaft goes straight into the gearbox and is the perfect length. Coolant hoses etc all fit perfectly. Just too good a conversion compared to RB26DETT.
I got around the electronic -> cable speedo problem by retrofitting the R33 instrument cluster into the dashboard.
The GTR with RB26DETT was also always in the pipeline, so I wasn't too concerned....
Gerard