Man! I miss that 2400 rpm sound! Put more than a few hours on Dad's 660. He rigged an onland hitch to a pull type 6 bottom, and ran duals on it. Good times
I was looking for a bigger plow tractor for our hobby farm in 1984 and was ready to buy a IH 660. The only reason I didn't is that I couldn't find a quality pull type plow that matched the capacity of the tractor. It could handle six bottoms in our soil, but a pull plow of that size was a rare bird by then.