Hello: l bought a mustang 545 this past fall. I agree not much information out there on them. Mine has a Perkins 4.154 Diesel engine. So far it has run well other than the fuel pump went out the other day. If you want the story on replacing that let me know. This machine is a beast! I think it was the largest skid loader built by Mustang in its day. Since my serial number is GA 00393, I would bet there were not many made. I had a Mustang 441 with a Perkins 4.108 before and the 545 will work circles around it. I also like the flip open cab for easy access to hydraulics and fuel tank. The engine cover removal also is easy, 2 bolts and you have access to the entire engine compartment. I also have the original operators manual with many part numbers of common filters and replacement parts. When I get a chance I will post a picture of her.