It weighs over 10,000 with a car on it & will get 15 MPG. It,s kinda sluggish though. [/QB]
They're all kinda sluggish til you strap on a turbo. The 6.2's have to be limited to 10psi of boost due to thin piston crowns.
If you want to stay natural, moding the intake to get more air, turning up the fuel on the injection pump, and a set of Humvee headers from government surplus will get you some fairly impressive gain.
I've seen a '69 GMC for sale local to me that had a 3-53 detroit conversion. Been on the market a long time. I dont know much about them but 159 c.i.d. non turbo diesel seems like it might be a bit under powered?