The scoop goes something like this (iirc):
You could get either the 3 or 4-speed Saginaw in the '79 Pontiacs (Grand Prix/Grand Am) and '79 (and I *think* '80) Montes/Malibus/El Caminos... 2 or 4 door or wagons, didn't matter. Just depended on how they were ordered. Don't think '78 had them. I've seen combos of most of the above... and...
You could get a Borg Warner 5-speed (T-5?) in the '79 Cutlass as well (incl. 4-dr and hatchbacks). Only model/year for that one.
The pedals/bellhousing/flywheel/boot etc. on mine came from a '79 Cutlass 2-dr 5-speed, the trans and shifter from a '79 Grand Am 2-dr. The 5-speed had a bum 1st gear (growled like mad) and at the time ('90-'95) no parts could be had. The 5-speed had a short shifter that sat about 8" further rear-ward. It was a top-mounted "rail" shifter vs. the 3/4-speed forks....
They used those 5-speeds in Monzas/Sunbirds too, and they had a unique c-member on the cutlass. (different mount location)
Here's how you could get them for the '79 Pontiacs anyway:
Grand Prix: 231 V6 - 3spd only, 301 V8 4-spd only.
LeMans/Grand Am: 231 V6 - Either 3 or 4spd, and 301 V8 4-spd only.
Dunno about the Chevrolets, or why you couldn't get a 231/4spd Grand Prix(!)