[GT40FIED]

I'm pretty sure the flange design isn't universal, either. For instance, I'm not sure a header for an IHI turbo would mate with a KKK or Garrett turbo. I haven't looked too much into this, but I can't imagine every turbo having the same size/bolt pattern in respect to the mounting surfaces. Then again, most factory turbos on USDM cars come from either Garrett or IHI so interchangeability is probably not as hard as I'd imagine. Then, of course, you run into what Arnel was talking about. Since trim selection, A/R ratios, bearing setup, wastegate type, etc. are so important to turbo selection I'm not sure I'd just grab a turbo off of any old car and toss it onto mine. Look at Thunderbird Turbo Coupes and Mustang SVOs. Both had T4s, I believe (the T-Birds may have been T3s...but fairly similar to the SVOs) and had VERY different capabilities. Likewise, I've seen people swipe the T-Bird (or even SVO) turbos and throw them on Mustang GTs and wonder why they run out of steam so soon (hint: twice as many cylinders).