FWIW, stock rubber L bumpers were made with a large flat steel bar under the rubber. That (and the hydraulic shock mounts) are why the thing weighs so much. What happens over time is, the rubber coating shrinks up and most did not quite cover all areas underneath; water gets in. Rust expands the steel and bingo- you got waves from rust swelling under the smooth rubber.
A few owners have fixed the problem by cutting away the rubber where its wavy, derusting the steel bar, then regluing what left of the OEM rubber and finally, recoating the whole bumper-face with liquid rubber. No, I don't remember what brands or where they got the supplies but there was a POCA Tech article on it decades ago.
I looked at the problem on our '72 L, and bought a fiberglas replica that's 20 lbs lighter. Few pristine rubber bumpers exist and none are cheap. Shipping is a problem due to the sheer size & weight- truck express is often the only option. Be prepared.
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.