Dalmar, thats what I did 3 years ago when some kid ran a stop sign and totaled my '91 F250 ext. cab 4x4 with a 460..... I was tired of 6-8 mpg while towing my 21' super vee.
Anyway I found a '94 PSD extcab 4x4 with 75,000 miles on it....even matched the color of my Alumaweld.
So now I haul a '95 9'6" Elkhorn camper and tow my 21' supervee and get 12-13mpg..or 18mpg empty..double what my injected 460 would do... Living in Selah I have to pull White pass or Satus pass every trip,
and the PSD dose a great job...plenty of power.

From what I've read and talkin to people who own them 200,000 to 300,000 miles is common on this engine