My buddy did this swap.
He used a Downey kit (advance), 3.8 buick, TH350 to his stock t-case.
I think he's moving to v-8 power with a manual.
Do you want me to ask him if he's willing to sell the adapters?
Overall the conversion makes a fine driver and good all around trail truck. he hasn't bust anything in 4 years.
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75 FJ40, 4 inch BDS springs, 1inch body, 35's, detroit EZ locker, power steering, disc brakes, 3spd low range gears, full cage, XD9000i, extended shackles, dual batteries....you get the idea.