The only County's that I have seen were the Super 6's. They were based on the 5000. However, I do think they did conversions on other models, the 4000 probably being one of them. County's forte was adding FWD as an aftermarket setup. When Ford started offering FWA as a factory option in the late seventies, County was not long for the tractor business. The serial # you posted (B928819 ) would likely correspond to a 1973. This is a Ford Basildon produced serial number. 3D26c is a production date code of some component or another, which reads as 26th of April 1973 (likely). It could also be an '83.(The cycle repeated every 10 years.) If the engine block is smooth, then it's probably the 73, if it has external ribbing it is definitely an '83. County, from what I know basically involved themselves in adding FWD to a standard Ford skid unit (Basildon). So, most parts for the tractor proper are simply Ford parts, easily sourced from NewHolland, or this site and others. FWD parts, I don't know about for sure. As far as I know, County went bankrupt. I'm guessing you would be S#it Outta Luck in that dept. Post a pic if you can. That sometimes helps to id the tractor better. Otherwise, the specs should be the same as the Ford model skid it is based on. HTH.