The MPHS has car lettering diagrams for some heavyweight cars (they sent me a couple on request) and I'd assume for some lightweights as well.
Early on MP used to wax or clear coat their passenger diesels, but I'm not sure when that stopped.
MP had 4 E8's and 36 various PA's, early on they ran in like sets, with the PA's using E7B's as a booster if more power was needed. On mainline trains (Texas-St. Louis) aound the mid 50's they seem to have mixed E's and PA's indiscriminately and by 1960 or so started adding torpedo tube GP7's.
Secondary trains used F units, FPA-2's and torpedo tube GP7's from dieselization.