www.jdrace.com

Hi! I have a 72 Chevelle, small block SS VIN, and it has a 454, with a ten bold rear end with 410 gears. The rear end does not seem to fit well in the car. It looks like i will have to shorten the upper trailing arms to 9-1/8 inches to get the pinion rolled down to get good driveline alignment. I've been having trouble identifying the axle but now see some Olds pictures which seem to match. Casting number 1235198. Ring gear has what looks like left hand bolts with 5/8" heads. There is a large raised S on the front of each side of the casting. Is it reasonable that this was not a direct bolt in for a Chevelle?

Need to see the rear end panned out mounted. That mightr be a 73-77 rear under the car which has the upper control arms in a totally different angle and the lower arms may also be an issue if they did not change them to the correct spots also.

Jim
J D
Or get us a casting number from the center section casting.

Casting number for the pumpkin was in my post, 1235198. I can't find it referenced anywhere. Lower arms are boxed, but it looks like the axle has had no modifications, and things don't seem to fit. The symptom was a broken transmission tailshaft housing. I don't know if the excessive rear u-joint angle (about 7 degrees up while the front u-joint angle was 1-12 degrees down) would have caused that during tire spin, but I had just replaced the bearing and seal while changing the shaft gear to correct the speedometer. I sure appreciate your help. I'll try to get a wide shot from underneath, the lower arm bushing look ok each end, the upper bushings are stressed in the original 7 degree angle (picture) and are way off when I get the axle rolled into where it needs to be.

OK, got a few more pictures, hope these help. The axle is oriented so the pinion angle is right in these photos. The upper arms are disconnected from the axle only, so you can see the alignment offset. The lower arms seem to fit pretty good, to me.

More

The rear is a 1973-1977 era a-body. NOT EVEN close to the right rear in your car. You will never get thaT THING IN CORRECTLY AND IT IS ALSO ANOTHER INCH WIDER THAT THE 68-72 REARS. AND 2" WIDER THAN THE 64-66 rears... So you will have al kinds of issues with that set-up. Sorry . Jim

OK, thanks for the information. I guess I need to start looking for a rear end. It doesn't really look too wide for the car, but the mounts are sure off. Would the carrier bolt into a correct rear housing? Are the top lugs the only ones in the wrong location? Or are the lower attachments wrong too?

Does the assembly I have have much value for resale?

You can use all the guts IF you find another 10 bolt 8.5 from a 1971 1972 Cutlass or Skylark. IT CAN NOT BE a rear from the 1973-1977 era.

YOU need a rear from the 1965-1972 era a-body GM
So GTO Lemans Tempest cutlass 442 SX supreme, Buick skylark GS or 1970-1972 Monte carlo
69-72 Grand prix
Chevelle, El camino 65-72

These will all bolt in correctly but could have different guts as some will be 12 bolt cover and 10 botl covered and different ring gear and pinion sizes such as 8.2 8.5 8.875 etc.

THE housing mounting points is where you need help here.

1971 1872 Buick skylARK AND oLDSMOBILE CUTLASS ARE GOING TO BE YOUR EASIEST SWAP INTO THIS SITUATION YOU HAVE AT THE MOMENT.
Sorry about the caps in and out...typing s way off this morning...

Jim
JD

Thanks for the reply! Lots of great information.

If I fabricate offset upper arms to fit into the bushings at each end, in the loaded position, do you expect the axle assembly will get into a bind before it will get enough travel? I thought I'd make two links out of 1/2" rod before I fabricate something, to see whether the axle rotates too much or gets in a bind during travel (I have the springs out hanging from all thread right now with the pinion shaft in a good position at the loaded elevation).

Still worried about the lower being too wide and the shock studs are not in the correct spot nor is the spring perch in the correct spot. THAT rear is just totally the worst era to try to fit the 65-72 era... A G-body rear would be easier to install in the Early A body rear. I do see they did change the spring perch mounts to fit the era of 65-72 That is good. Jim

For a followup, I went ahead and fabbed some upper control arms to fit when the axle was rolled for the proper pinion angle. They were about an inch shorter than the Chevy arms. But with them installed the shocks now fit. And i have no binding in travel from bumpers hitting to hanging on shocks. Matched angles between tailshaft/drive shaft and drive shaft/pinion. No driveline vibration.

Neat... If you can get it quiet and vibration free that is key. Jim