Denny - suprisingly, it looks like it's epoxy ester primer, epoxy being pretty tough of course .... and electro-deposition was invented/discovered in the 30's - Dupont says you're right, Ford started common automotive use in '63, but these e-coat technology suppliers claim some form of it was being used in the 50's .... interesting stuff, especially that first link

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot