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.
" 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.
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "