12-bolt Chevy Upper Control Arm controversy

There's been numerous discussions of a "special" upper control arm for the GM A-body 12-bolt rear end.   Here's some pics that show the difference, and that it's not that big of a deal if you had to adapt  a "standard" arm to the driver's side upper bushing of a 12 bolt rear.    

Click the images for larger versions

Arm on top is a stock 1971 Olds upper rear control arm.   The lower arm (black) is from a (supposed) 1969 Chevelle SS that had a 12-bolt rear.   As you can see, the SS arm is notched and reinforced below the  bolt hole.

Closeup detail of the 12-bolt upper arm. There's a reinforcement plate spot welded over the hole from the factory.

12-bolt upper arm on a 12-bolt rear.  Not shown is that the passenger arm is the same for all rears, no clearance problems.

Non-12-bolt arm on the 12-bolt rear.  Note the interference with the carrier housing.  This could be fixed with a grinder in about 30 seconds.

Just a comparison of the new 12-bolt rear with the stock 10-bolt BOP rear.    The BOP rear did not appreciate being behind a 403 Olds with a 700R4's low 1st gear.

This is a set of F41 suspension braces.  They go from the upper to lower control arm mounting points.
Thanks Ebay for a great deal on both items.   The arms were only $20 because they were dirty (ebay bidders hate to clean parts), and the rear was ~$150 because the guy had it listed wrong and wouldn't ship it.      I bought the F41 braces for ~$45 as shown, easier to pay $45 for bolt-on's instead of $40 and I have to clean and paint....  
If you're doing a A-body rear end, get a set of the F41 reinforcement bars and use Poly bushings.   Just grease well and they'll be no squeaks - these cars handle *and ride* much better once the ass end isn't sliding around like a Armor-All'd bench seat.  
Soon to follow, front big disc brake conversion done the right way.  
More useless facts from the degenerates at grimers.com
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