I also have 4 AHM c-liners. When I got them they were very common. They are only powered on one truck, but it is self contained. I got a bunch and double powered all of mine, it is a drop in job. They are still running after 25 or so years. I have two converted to DCC now and 2 on the shelf. As mentioned, the mechanisms are lightweight, but seem very well engineered to me. I filled ithe big holes in the pilots, shaved off the cast grabs and added wire ones, and put on PRR antennas. I also repainted PRR freight scheme. I did kitbash a B unit out of 2 As.
All nation produced EMD F7s, F3s, and NW2 switchers. These were handed down through a couple of companies over the years. I think General Models was the immediate predecessor. it was All Nation from the 60s or earlier until Bill Pope died a few years ago. There was also a line of steam engine kits there generic and included a 4-4-0, 4-6-0 (B&O prototye), 4-6-2, 2-6-2, 4-4-2 and 4-8-2. The 4-6-0, 4-4-2, and 4-6-2 are pretty common and show up used at shows at decent prices. The diesels were pretty much screwdriver assembly. The steamers required some soldering for detail work.