69 rear end in a 67 question
 

so I have a rear end from a 69 Chevelle in my 67 Tempest it's been in there a long time but I've always had a strange scraping noise (like the car was bottoming the exhaust on the pavement unless I had more air in the air_shocks than I would like to have...... well recently I pulled that rear out to have the 4.10 gears swapped out for some 3.55s and I found the scraping noise was actually the driveshaft making intermittent contact with the top of the tunnel.
so my question for you that know more than me do I need to be running the shorter 68 and up upper control arms to tip the rear down more in front instead of the longer 67 uppers (would it even bolt up with the shorter ones?) the rear is at a shop so I can't test fit anything ....
any insight would be appreciated.

Thank You

Use the correct 1967 control arms.

The rear ends all swap from 1964 - 1972 A-body GM cars, always use the control arms that match your chassis.

Driveshafts contacting the tunnel isn’t that uncommon, that issue isn’t caused by your rear end or control arms.

Ok Thank You B-Man! I do have the 67 control arms in place now I was just racking my brain (what little I have left) on what the issue is with hitting the floor as I would really like to go without the air shocks.

I have 1971 Olds 8.5 10-bolt that I recently purchased installed in my 1964 Le Mans, using all the original 1964 control arms.

If your driveshaft or front output yoke is hitting the tunnel look for a bent transmission crossmember. Sometimes over the years a jack might have been used under the crossmember to raise the car and bent it upward causing driveshaft interference.

Hmm that is a good great thought I do have another crossmember I could put in while it's still up in the air and see if it all sits different.
This is why I come here with my questions :D

Again Thank You

Many years ago I had the exact problem "b-man" was talking about with my 1965 GTO. Drove the car over the lift at work. Attached a chain to the cross member and the lift and then lowered the lift slightly. Bingo! Clearance created.

Difference in control arms from the different years? I have some unknown year boxed one a Buick buddy gave me. I suspect 68-71 range

the upper control arms on my 67 measure 12.75" center to center and the 69' upper control arms on my Lemans measure 10.25" center to center

Thanks. Lowers different also?

Lowers all the same 1964-1972.

I checked the crossmember over the weekend and there is no apparent damage I guess my next question is does it matter that the crossmember is also from the 69 Chevelle the 12 bolt rear is out of ? I guess I don't know if the crossmembers are fully interchangeable ..... I used it because it bolted in instead of the saddles maybe that is my issue??

Thanks B man!

The Chevelle crossmember could be an issue.

I would try the Pontiac crossmember and see it that helps.

You can also eliminate the rubber cushions at each end of the Pontiac crossmember by simply drilling holes in it and the frame and bolting it in.

I had a 1964 GTO bracket race car that was done that way, it was already like that when I got the car. This will also lower the crossmember by a little so that might be helpful.

I do have an original crossmember in the shop so I think I will take your advice and swap them out!
Thank You for your help B-Man it's greatly appreciated as there is basically no other real Pontiac people in my area to bounce these kind of questions off of.

I,ve had that problem before to. I jack the front floor brace with two jacks
to get the clearance I needed work great. these old cars get sone sag
over the years and we have to help the out time to time.

GT