About a year ago I bought a replacement rear bumper for my '66 98. Like a lot of Olds of the period the outer edges are sort of like ears. It was not NOS, but the chrome was good and it was nicer than the one I had, so I stuck it on.

On delivery, my right rear "ear" seen here as item #1 on the lower diagram was cocked slightly outward at the top about 1/2" proud of the passenger fender line.

You can slightly rebend bumper ends with a ratchet strap. My right rear edge was out of alignment to the rear quarter, a little creative bending and it's where it should be.

I'm getting a little detail oriented due to my recent body work project, so this morning I took my second run at using a ratchet strap to pull the ear "inward" about 1/2".

The first thing to do was to remove the trim piece seen here as item 13 (98 Only). These are diecast chrome with 5 3/8" nuts securing them to the bumper. They break extremely easily and are rare now. Especially the screws on the back. If you can remove it before bending the bumper, do so. If you feel it crack or the nuts wont spin on the screws, it probably wouldn't hurt to leave it on. I've broken a bunch of these screws over the years. Short of welding, there's no repair that's occurred to me.

I looped the slippery nylon strap around the outside of the ear and connected the hooks to the very strong steel frame connection, seen here as the 2 "T" shaped slots to the left of the number 5. Tightened the ratchet a few times slowly, popped it open a few times and I got the movement I was looking for. My measurement was 6.5" inches for the gap before bending and I got to the 6" I was looking for. It's 1/8" tighter than the left, but looks much better.

Now the right ear lines up with the passenger rear quarter like it should. The bonus was I made the bumper-to-rear quarter gaps down around 5/8" which is just about where Olds wanted them long long ago. The final step was spraying just a bit of silicone lubricant on the bumper rubber shims so they don't squeak now that they're tight.

I suspect this mild bending method would work well for placing and shaping the 66 big car bumper ends as well, but mine are pretty much where I want 'em on the convertible.

Fun small morning project. Took maybe an hour or so to get it right.

cf

 

I massaged the bumpers on my 72 as well. I Did some work w them off and some w them on the car but IMO I was able to make a big visual improvement w a small time investment similar to your own experience.

 

I tied a 64 Belair after an accident between a couple of big trees, pulled and straightened the rear X frame with chains and a come along. The rear corner panel was bent (actually bowed) completely under the trunk lid.

 

I was looking into this myself on the bumpers of my 71 cutlass when I came across this handy tool, a hustler stick. There are some youtube videos for using this and it looks like something you could fab yourself easily enough with a 2x4 and some chain. Never heard of it before, but then again I don't straighten bumpers for a living.