After crunching numbers and going through a lot of things, realized that the blown out 10 bolt differential would probably be easier and smarter to replace with an already working 12 bolt. I found a 12 bolt 3:07 ratio from a 69-72 Chevelle and wondering if it will bolt right into the 76 Monte. I see that they're both A-bodys but the Chevelle sticks out a couple inches more?

Thanks for any advice on this subject.

 

Short answer: No, the '73-'77 A-bodies are wider. I don't remember how much. Depending on how much HP you are planning on running you might want to look into one of the aftermarket Ford 9" rear housings which can be purchased with the proper mounting brackets already welded on for your 2nd gen Monte.

 

The body maybe wider....


1972 chevell wheel base
Wheelbase116.0112.0116.0Overall Length201.5197.5206.8Tread - Front60.059.3Tread - Rear59.959.2Overall Width Car / Body75.4Height53.352.7 / 52.954.4


wheel base of a 1976 Monte Carlo
Length:
5403 mm / 212.7 in
Width:
1971 mm / 77.6 in
Height:
1339 mm / 52.7 in
Wheelbase:
2946 mm / 116 in
Front track:
1572 mm / 61.9 in
Rear track:
1542 mm / 60.7 in
Ground clearance:
120 mm / 4.7 in

Wheel base is exactly the same..... On Both!
Looks like your in Business!!

OR

Why not put a mini spool in the 10 bolt?

 

Unfortunately, the wheel base is not the dimension that you need to be concerned about with this swap.

You need to look at the rear track. There is 0.74" difference between the 68-72 A-body an the 2nd gen Monte. So the inside of the brake drum will move to the center of the car by 3/8" on each side. You need to make sure that you have clearance between the frame rails and the inside of the tires. Once you get past that, you might need to relocate the controlling arm mounting brackets.

None if this is saying that the swap won't work. I'm just saying that it probably isn't a direct bolt in replacement.

 

iceman5, thank you, I couldn't have said it better myself