I'm using 87-88 Tbird turbo-coupe gears. So far so good.(3.55-3.73)I have 3.73
You can get 3.73-4.10 from f-150(just the gears). However the carrier is 31 spline so you would need axles.
Tbird is cheapest option
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82 Mercury Capri 302.
Comp. Cams
Tremec 3550
3.73's
12.8@106 N/A
Kevin's Capri