Not sure if you need to be signed up
http://www.redlinegti.com/forum/viewtop ... en+mk1+mk3
http://www.redlinegti.com/forum/viewtop ... 15&t=25041
MK1 has a different intake/fuel rail and the air flow meter on the intake manifold on top of it while MK2/3 has it on the airbox (if that makes sense)
The thermostat housing is different also
MK2/3 are pretty much identical (computer on MK2 is 128rom while MK3 is 256....few other small differences in the loom etc)
Im sure there are alot more things and people on here will be able to help you ou.....maybe PM jonno_racing as he know alot more....he's been tinkering with these engines and doing a few conversions
Also have a look on redlinegti.com forum
If you're going to do a conversion into a sierra...try finding the MK1 as it's abit easier in regards to the dizzy setup