Without knowing more details. I"ll offer a rough speculation:
Since its a diesel, it means its a Deluxe.
Power Steering, Multi-Power, Pressure Control, Flat Top Fenders and the cushioned seat (float-ride?) would all be options.
Live PTO would be standard. Independent PTO would mean it has multi-power.
If it"s above SN 9A-38XXX it will have an alternator (roughly 1968/69)
Speaking from experience and depending on how well its been maintained, I would check to make sure the rear wiring harness or at least the rear work light assembly is still there. The harness and work lights are no longer available from Massey. I would personally be willing to pay a little bit more for this.
Assuming it was all there and in decent shape, I"d pay 3-4. I have the Continental Gas Z145. They"re really good tractors.