[trooper Tdiesel]

being a 1972 is very nice, you can mod the engine/drive train in any way since your 100% DEQ exempt.

be a bit of work but swapping to a manual trans whould help.
also look in to how many gearing differences there where back then.

its likely geared like are delivery truck before we changed things up.
3sp auto and 4.11 gear makes for about 3,000 at 60.

if the engine is the 440ci swapping to a 318 would help as well.
i know more then one person that can get high teens out of a 3/4 ton with a 318 where the 440 is REALLY BAD MPG, LIKE 12 IN A EMPTY TRUCK
the 360ci gets about the same mpg as the 440 so i cant reccomend a 360 my self.

i do know one person that did a swap to a ford 6.9L with the ford 3sp auto trans and it turned in to a 9 to 13 mpg auto. it was 3.5 to 7.5 mpg with the 440
aro mods, diff swap and a manual trans would have taken it to the high teens or better.

an electric fan would be a good idea, unless it needs more cooling on a long grade do to being around 10,000lbs
clutch fans can take more btus of heat out of the coolant in less time then a electric, thus why big rigs still have them.


even if its a 440 and 3speed auto, getting about 6 mpg and you don't mess with that.
"MAJOR" aro changes should get it an avrege near 9 mpg at around 55mph