As per a conversation I once had with an engineer at the GM Muncie plant, he reported that the Fiero transmission was designed for a maximum torque of 200 ft. lbs. The 3800SC puts out more torque than the design limits. The transmission may last for around town use , trips and occasional full throttle use so determine how you will use your powertrain and then choose the parts. With the stick you will also need a HD clutch but keeping the 4 speed does greatly simplify the swap.
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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "