Marv, your rpm/speed numbers look very close to mine with 4.10s, the GV OD and 34" tires. I'm averaging 21mpg, up to 23mpg if I baby it at 65mph on the highway.

 

Granted, it was a 2wd, so wind resistance isnt quite as big a factor, but I think rbrettctd has seen 25+ with his 3.07/ Getrag combo, when he only got 19-21 with the auto. Bookshelf- try driving 52-55 for a trip and see if you get a big jump in MPG. If so, it may be worth a shot at the 3.07s. If you only see 1 or 2 mpg, maybe not.

 

Ya my avg is around 22-24 flogging on it and running 70-80 on hwy. Personal best of 28.3mpg hwy, no b.s. I love my 3.07/5sp combo, though its not the best for racing off the line .

 

That 3.07/ getrag combo in a 2wd would step the MPG up the next notch. Having the truck lower to the ground and the lesser weight would give you even more of an advantage. With what my truck does I could see breaking 25mpg.

 

If anyone needs spoem 3.07's for tehr 5-speed 4wd I will swap axles so I can get a lower gear in my pulling truck.

 

Got 4.10's and want higher gears. only thing is. my front is a Dana 44HD that im using for my 4wd conversion. cant find a 1st gen Dana 60 here anywhere.

 

theres 2 dana 60 fronts on craigslist, in montana, ones is just the front end and the other is in a chevy truck, 1,000 bucks for the truck

 

Marv, thanks for posting this, its good info to have.