how hard will it be to put a Monte rear into a third gen. what kind of fabrication will be needed for the car or the rear. and what size is the monte rear.

 

Depending what year the Monte is, it could be an 8.5 or just a 7.5 like a third gen.

Doing a diff swap like that isn't that easy. Providing the diffs are the same width and I doubt they are, you would need to cut all the mounts off the Monte diff. You then cut all the mounts off the third gen diff and weld them onto the Monte diff.

Now comes the hard part. There's no easy way to attach the third gen's torque arm onto any diff other than a third or fourth gen. That's what makes junkyard diff swapping into a third gen very hard. It's not impossible, but very difficult. By the time you're done fabricating and modifying, it can be cheaper to buy an aftermarket 12 bolt or 9" designed to bolt right into a third gen.

 

ok so what would you recommend. im gonna probley be getting an 89' r/s to build with.. where can i find a rear to use with this. i was wondering about the monte rear cuz my friends boyfriend used a monte rear so i wanted to find out

 

depends on your wallet size and/or fabrication skills

if its not a third gen f body axle then it will not be easy


thats the biggest downside to these cars IMHO

putting a rear under it that is not stock factory correct is a huge PITA unless you have lots of $$ or lots of fab skills



and as far as monte rears go it was not the year but it was the package


some SS and some GN and some turbo regals got the 8.5"

it was not year dependent


you can pretty much say '78-87 on these; that body style in particular

most all these G-body cars got the 7.5" however, and any true G body 8.5" still left and that are around are going for lots of $$$$$$$$$$$$$$$$$$


other cars these years got the 8.5" as well

B-bodies with towing or 9C6 or 9C1 package did- through '96

and all the wagons did

also SOME '77-82 pickups/vans(G-10 and G-20 both), and ALL '83-up pickups/vans(half ton only(half ton = 5 and 6 lug wheel hubs))


you can get a dirt cheap 8.5" the same one as a G body one from most of these other vehicles, especially wagon and caprice and delta 88 and so on, super common, dime a dozen

mounting the third gen F body torque arm to the axle housing is going to be the problem

after swapping the spring coil mounts(cutting and welding required)
if swapping to an axle other than an f body one was feasible without any major pain then id have done it years and years ago under my 82 with one of the billions of 8.5" and 12 bolt car and truck axles i have taken to the shredder over the years


but its not

so.,..
right now i have an 85 cutlass supreme(oldsmobiles version of the monte) but it has the typical 7.5" under it in which is under 95% of them all


i have also had other G body cars from 78-87 including an 80 cutty supreme and a 78 grand prix and also were 7.5" of course



just a few of the billions of vehicles i have had:
http://smg.photobucket.com/albums/v2...spastvehicles/

the 78 GP i had:




8.5" was installed in only a few "rare" instances

good luck

 

I recommend you use what's currently under the car. Change to some better gearing if required. If you break it, then decide how much you want to spend on a better diff.

Rough cost for a complete direct bolt in, ready to go, 9" or 12 bolt will cost you $2500-$3000.