2.73 3.08 and 3.27 were the only options. 2.73 and 3.08 were most common. Not many 3.27's. Now keep in mind these cars are 25+ years old, so that's a lot of time for people to mod them and/or repair them with different parts. I've seen them with 4.88's in junkyard. I've seen them with OE 2.73 and everything between. Found a '91 GT once in a yard, got excited (was looking for fuel lines from tank to engine for a v8 swap), got over there and popped the hood. 2.3. Somebody went thru the trouble of swapping a 2.3 into a GT for some reason. You never really know unless it's documented and that fact alone will continue to get "worse" as time goes on.
Mine had 2.73 (AOD), and it was OEM, never touched, bone stock 92 GT right down to the factory silencer, coil cover, spark plug wire cover and wiper motor cover. It now has 3.73. 2.73 with a 225hp 5.0 makes the car feel like it's 5,000 lbs. With the AOD, 3.73 makes it feel like it's 3500 lbs. 4.10? 3,000 lbs. Still a turd by today's standards but much better. I stuck with the 3.73 because it's a compromise between the 4.10's acceleration and the 3.55 highway manners. With 3.73 and the rest of the car bone stock it knocked out 24 mpg on a road trip which I found to be outstanding all things considering. My old car (5.0 85 GT 5 speed) had 4.10 and honestly it was a little too much. First gear was useless. Let the clutch out, you're pulling into 2nd almost immediately. Other car is a 93 coupe with a 2.3 and OEM 2.3L 5 speed transmission. 3.45 rear. First is almost useless like a 4.10 and stock V8/T5. I have a 3.35 T5 to go in at some point, but I'll have to change the rear gear to compensate for the higher OD and first gear, then have to get used to having to throttle it to take off from a stop in first. Right now I don't have to touch the throttle to accelerate from a stop, just let the clutch out, like a diesel. Once moving, yeah start giving it some gas to make a little speed and with it being a 2.3, very little speed at that.