The 7.5" rear was developed originally for the Vega. The Monzas and all Vegas 1975+ used a torque tube assembly with the drive shaft. As for the guts (ring & pinion) they made 2.29, 2.56, 2.73, 2.93, 3.08 & 3.23 ratio sets if I remember correctly. They also offered a 3.42 in earlier years before CAFE nixed it. The 7.5 center was even occasionally used on some full-size Chevrolets with 267s or sometimes 305s. Also the G-body cars it was common (Malibu, Regal etc).

 

What kind of engine / trans does your Monza have? With 2.29s I would guess a 305 automatic. In 1975 only, in California only, you could get a 350-powered Monza as the 262 V8 didn't pass California smog certification. I wonder which rear they used?

 

It has been a while since I have seen a once-common Monza on the road.

Often think about my little beast, my first car actually. I kept it stock looking on the outside. I suspect the rear end had some tall gears in it like the 2.29's

since it could run dead even with my cousins' 79 L48 Corvette on the highway, of course the 79 Vette routinely makes the 10 worst Corvettes made list. 

My daughters ex-boyfriend had a Monza for a short time and if I recall correctly the S-10 used the 7.5. As I had thought it would be a lot more convenient to go to 5 lug wheels and I had found a post on some monza lovers site. The axles were supposedly interchangeable and I would guess the rear gears as well.