I ran an R50 with an 8 row head for several years and that makes a nice match for the combine. In 150 bu., 15% moisture corn, you should be able to run between 4 and 5 mph. There may have been a corn or wheat version. If it has a variable header drive, then most likely it is a corn version. Maybe someone else can give some other details of some differences. Price wise, since it has had some repairs to it, I would guess you may be able to get it in the $20,000 to $25,000 range. The combine would be able to handle an extension but I would not use one if I had hillsides. Not that it probably couldn't handle it, but it would just be a lot of load on one side. It will be a nice companion to a 7720. Actually the R50 will outdo a 7720 most of the time.