Here are a few I've done.
The Lionel traditional size SD9 was originally a Chessie. I stripped and repainted the blue chassis (an awful job, Lionel makes that paint not to come off!), then swapped a Lionel GP9 body onto it. Finally I renumbered the body to a correct SD9 road number. The unit has TMCC; I did it about ten years ago. This was before MTH came out with their Rail King Scale SD9 in Milwaukee Road. The transfer caboose is a Lionel that I repainted. The Milwaukee had similar cabooses, but they were steel, not wood.
K-Line Shay, redecorated to Chicago, Milwaukee, & St. Paul. It's not well known, but the Milwaukee Road owned a few Shays in the early part of the 20th century. The log car is a LOTS special run; I have enough of them to make a nice train. Caboose is an MTH bobber.
This is a Williams SD45 that I did for the Gadsden Pacific Toy Train Museum. I designed the paint scheme to evoke the Sonoran Desert, with the desert tan and red rock colors. I still need to print some decals and clear-coat it, then I'll donate it.