That baby looks to be in cherry shape body wise.
A few things are missing. They came standard with a 2000rpm rear pto, turning brakes, 3PTH and the deluxe seat. I dont see any of those on this machine. Without those $900 is a bit steep to me. The rear PTO you can live without (ebay $200-$400) but the 3PTH is a necessity if you want to use this as a garden tractor (ebay $300-$600). The original deluxe seat can run upto $300 but its not a necessity either.
The weak points on the D series is the transaxle and hydrostat. The rearend suffered from a design flaw in the begining. They used 5/16 grade 8 bolts on the ring gear. These would break and cause all kinds of havoc in the rear end and the hydro. This was fixed by WH in the later years of the Ds by using 3/8 grade 8 bolts. (I upgraded mine from the 5/16 to 3/8 grade 9) This one being a 78 it should have the 3/8 bolts, but you cant tell unless you split the rearend.
Most Ds that you find on CL have hydro problems. I dont know why, but the hydros seem to have high rate of problems as compared to other hydro models. Mine was no exception, the hydro wouldnt even pull it up the ramps on the trailer. I rebuilt my hydro and hydro motor.The main problem was scoring on the valve plates. It wasnt a fun job but it wasnt bad.
That all said, they are a beast of a machine. They have the weight and traction needed for heavy pulling and moving. The engine has tons of torque and are cast iron. Once you get into them, they are easy to work on. My deck is 40 years old and I just rebuilt the spindles and patched all the holes (swiss cheese). My wife just mowed the yard with it yesterday and the place looks like a golf course. I wouldnt trade my D200.
ETA: looking at it again, its possible that it is a D180. Its the same as the D200 but the engine is a K431 (18HP) instead of a K531(20HP). The 180s did not come with the deluxe seat, 3PTH, turning brakes or 2000rpm PTO. Check the kohler model number to be sure. WH used a weird model numbering system with their tractors so you actually have to look up the number from the name tag.
Edited by coldone, March 30, 2013 - 10:47 PM.