1969 Chevelle 396/325 automatic.
I took the rear upper control arms off to change the bushings and got them mixed up. I noticed that one of them has an extra tab spot welded where the bolt goes thru. How do you identify the left from the right.

Thanks
Ed

Ed, there is no left of right. I have seen some control arms with the tabs and some without. You ended up with one of each.

I don't think that's true. The reinforced upper arm goes on the right. I believe these were usually connected to 12 bolts. I have also seen them with the SS frame-upper-arm connectors.

I agree with DG that there is a difference. The one with the extra welded on tab is because they had to grind some of it away to fit on the 12-bolt housing on the right side. After grinding, there is not a lot of metal left betweeen the bolt hole and the edge, so GM doubled up on the thickness.

Otherwise, on a 10-bolt rearend, I don't think it makes a difference.

Hope that helps...

I dont think the tab is there because of the 12 bolt, I have used "regular" arms with 12 bolts and they fit fine. IMO that is a F41 upper control arm that came with the F41 rear suspension setup. I just brought home a very original 72 chevelle SS 350 2bbl car (I believe this is the only 72 SS version that came with the 10 bolt since my SS350 4bbl car had the 12) and it has the reinforced upper control arm on the passenger side upper as well as the rest of the F41 suspension. I have also gotten this reinforced arm from 12 bolt equipped 70-72 monte carlos as well, but they arent 12 bolt exclusive IMO. I would think the extra tab is to keep the mounting hole from getting egged out, which happens with the stock arms if the car is hammered hard..so I would consider it the "HD" part that would be installed in SS or HD rear suspension equipped cars.

The arms are left and right for the 12 bolt. If you notice the difference in room between the inside of the mounting ears on the rear housing you will see that the housing is a lot closer to the arm on the left side of the housing. If you try to put the right side arm on the left side you wou't be able to pull the arm down far enough to get the bolt through. The factory arm for the left side was trimmed down to clear the housing and then reinforced with the washer to give it strength.The reinforced arm goes on the LEFT side not the right.

I agree the arm should go on the left side..sometimes I cant tell my left from my right! But my 72 SS here has it with the 10 bolt rear, and I have swapped in 12 bolts in place of 10 bolts without changing control arms, so I cant see how it is a special arm for 12 bolts. If that were the case it would be needed for 10 to 12 bolt swaps, and it isnt.

Interesting. Neither side has them on my 70 12 bolt. You got me wondering. :confused:

Hmmm, I have a 65 12 in the 67, never noticed any difference in the arms. Makes no difference now, it's all been replaced with after market stuff graemlins/thumbsup.gif

I agree with coop. I have a 65 with 12-bolt. The arm with the the extra tab fits on the left because the clearance issue caused by the ear location on the 12-bolt housing.

Agree here too, in fact, I just finished grinding and reinforcing the left trailing arm on the '65 to get it to clear the 12 bolt casting!

Originally posted by 70Z15:
Ed, there is no left of right. I have seen some control arms with the tabs and some without. You ended up with one of each. graemlins/clonk.gif

I should have thought before I responded. I went back and looked at my 'before' pictures. You guys are correct. http://www.chevelles.com/showroom/70Z15/Feb22n30.JPG
The left side was reinforced.