got an 87 regal, (havnt been under it yet) but was told it has a ''rear end out of a monte ss'', now is that the same as the GN rear end, how can i tell difference, is it a good rear for a drag car, any thoughts on what should be done to build it to take a good pounding, wont see the street, i would like to do this cost effective, so if if i can use what i have cool if not should i look for a gn rear or an aftermarket one, thanks...
I believe the montes came with a weak 7 1/2" rear and the GNs came with much stronger 8 1/2" rear. The 7 1/2" rear cover is oval and the 8 1/2" rear is more round. The GN rear is way better for drag racing and you'll probably end up destroying the 7 1/2.
ok, i'll have to try and get under it this week and get an eyefull of whats under there, i'll cross fingers for the 8.5 then, thanks for the reply, john.
The Olds 442 of that period has the good 8.5 rear w/3.42 gearing. Those are tougher it seems to find than the TR rears. Monte SS has the 7.5 as mentioned. I'd pass on that and hold out for the 8.5
Difference between the 7.5 and 8.5 rear in g-body's More than likely your car has the 7.5 rear the easiest way to tell is look at the rear end and at about the 5 o;clock and 7 o;clock marks you will either see two tabs that to me either look like fangs(which is the 7.5 ) or look like (square boxes the 8.5)all 442 and hurst olds except for the 83 hurst came with the 8.5 w/3.73 gears, all the grand nationals (but I"m not sure on the t-types-I want to say yes but don't quote me) also came with the 8.5 but with 3.42 gears. The best place and easiest place to get a 8.5 out of a G.N. is turbo buick.com they go from anywhere from 400 non posi up to 850 w/posi, if this is a strict race car you might want to get a non posi one and run a spool it may be cheaper that way but thats just my opinion. If you want one from a 442 look on realoldspower.com but those are harder to come by, Good Luck Dan
No need to worry about finding an 8.5 I believe Summit and Jegs both sell a kit for $250-300 to install a 71-2 Cutlass/Skylark 8.5" rear into the 78-87 G-body. Kit makes it a bolt in process and you should have a much easier time finding a 71-2 rear.
Yeah I heard of guys doing this but the problem I believe was that the 70's rear end was actually a little wider and you got into back spacing issues! thats why alot of guys went for the GN or 442 rears (straight bolt in)
I think the only difference is 1-1.5" overall. I think a 71-2 rear from backing plate to backing plate is 53.5-54"
looked under it real quick,cold out..but in a grease pen says - 86 monte A-O, that narrow it a bit? will get under closer and get a good look at the shape and compare to a jegs catalog or look for a part #.
