Hi, Jeff D.
I have not personally had anything to do with the smaller AC crawlers. I ran an HD16 for a while and worked alongside HD21's on the same jobs.
The bigger AC's seemed to have issues with transmissions and final drives, although not as bad as the bigger International machines. I don't remember hearing anything in that line about the smaller AC crawlers or track loaders.
AC bought out Buda to get the engine manufacturing facility and they certainly worked OK in the HD16 that I operated.
Definitely check the undercarriage before buying. If you don't have the necessary knowledge, find some-one who does to help, even if you have to pay them. It could well be cheap insurance.
Hope this helps.
You have a wonderful day. Best wishes. Deas Plant.