John Deere Model 54 Rotary Cutter

Hello I am looking for some information on a rotary cutter I just purchased. It is a 4' John Deere model 54. I have found the unit on the John Deere parts website and a few other parts websites, but I cannot find any specs on the unit. It looks fairly well built, but I wanted to know if it is considered a light or medium duty cutter, what size saplings it can handle and what years it was produced. I would appreciate any information anyone would have. I plan to run it with my 1989 JD650.

Thanks