A couple weeks ago I found a 64 Buick Skylark more door in a salvage yard, and bought the front drum brake backing plates, and the stuff attached.

Thought they might fit the front of my 66 Malibu which has holes worn in the backing plates.

On comparison of the two sets, the springs seem quite different and the anchor pin is different on the Buick units.

Any idea if the backing plates themselves would work?

You would think that all GM A-bodies from '64 - '67 would share brake drums & components, but there were some variations. As an option, metallic shoes were combined with special heat-treated return springs on some. Also, some Buicks (Gran Sport 400) used aluminum front drums for faster cooling. Except for the Z-16, I think that all others used variations on the 9½" drums (ridiculous really, GM should have used 11" drums for the faster cars.)

No, I can't directly address your question, but I'm putting a few things out there. Hopefully somebody has some specifics to add.

Ron, if you are doing the junk yard circuit get yourself a copy of "Chevelle Hollander interchange manual".

I picked up a set of 68 Skylark spindles and drums.
(I like the finned drums)
The steering knuckle holes are larger on the buick than the elky (66).
Different backing plates too.
Hubs used a different wheel stud than the Chevy version.

But I am imagining that the whole assy. will bolt up.
Gonna need some way longer wheel studs tho.

Would '70 Chevelle drum brakes work for you? I got a complete setup in my basement I'd love to get rid of.

-Dave