[A Cobra guy]

Joe, I have a Lincoln Mk8 IRS in mine. ( I believe it is the same, just an aluminum pumpkin) E.M. did it for me when they built the frame. As far as I know it is all Lincoln parts with custom shortened 1/2 shafts. After 75,000 miles it is doing just fine. It is a great riding set up for the street. Mine is not a limited slip and I seem to recall someone saying it won't work with this setup so check that out if it matters to you.
It origionaly had very tall gears but standard ford 8.8 gear sets went right in.
I have the Lincoln hubs and disc brakes which are the 5 bolt pattern. (I don't know about the cougar/t-bird)

Harvey R.