While the John Deere 40,50,55 series tractors still bring good money.
Try buying a low hour John Deere 7810. Those tractors seem to bring a real premium. As do models like the 4960 and the 8410.
In some cases more than they sold for new.
The 10 series JD's are probably the best ever.
(loader/general mid-size hp farm tractor)
(that will get the IH guys all riled up)
