I've seen a couple full size dodge and chevy trucks for USFS but they were either service rigs, normal pickups without a light bar, or were classified as a light engine.
I do have a FB group I'd reccomend if you'd like to see more vintage USFS info. It has alot of info on other 80s and 90s engines and non emergency vehicles.
https://facebook.com/groups/366971211187437/
(Edit) also have a few LAPD misc photos I'd like to share, pretty sure a few of these are service vehicles but I cannot confirm.