613b
Mick, I used to work on a lot of 613A,B and C models. The expensive repairs to look for are the hitch and the elevator drive. Look for cracks, welds and plate repairs in the hitch. Also looseness in the hitch pins. On the elevator gear box, look for any oil leaking from the speed reducer, when they run out of oil they will destroy themselves in short order, and it's expensive to repair ($15,000 - $18,000). the 3208 engine wasn't bad, and starts great. A lot of the problems associated with the 3208 were due to misapplication. Just take care of the service on it. The machine will ride rough if you try to go to fast on a rough surface, slow down and use the machine to cut off the high spots. Sounds like the price is affordable, but used scrapers aren't selling very well right now, If you have a major repair it may exceed the value of the machine.
OC