^^^ That's what I've read & heard. Most stuff just needed enough coating to look new on the lot, or get it through the warranty period.
I remember seeing new '68s on the dealers' lots - I was obsessively scheming how to get a '68 Road Runner at 17 - and most of the black parts weren't high-gloss.
Gloss levels differed a bit on different parts - memory tells me torsion bars, PS gearboxes, and radiators had more gloss than K frames & etc.