Dana 60 front axle toasted.

[84 M1008]

Ok, now that we've determined that re building the axle is the way to go, I might as well throw a set of 4.10's at it front and rear. That will drop my engine rpm's by 275.

 

[Blue Ox]

There's a lot of math involved in gear ratios and larger tires (which your avatar looks like you have) vs the engine's power curves. And if you're still looking at a Gear Vendors you'll want to sit down with a calculator before you commit to axle ratios.

 

[84 M1008]

I went to the rpm calculator shortly before my last comment. With 4.56 gears and the 37's I'm turning 2551 rpm's @ 60 mph. The 4.11 gears will put me at 2294 rpm's @ 60 mph. I may not need the GV after all. I figured the front axle has to be done anyway so I might as well do the rear also.

 

[Blue Ox]

The engineering really comes down to your intended use of the truck. What does it primarily do for a living and what do you expect to accomplish? Does it tow, rock crawl, mall crawl, local driving, highway driving? Do you want acceleration or MPGs? You may be okay with the 4:56s and larger tires. But don't expect the same acceleration with better highway mileage if you swap in 4.10 gears.

 

[84 M1008]

I'm looking to slow the engine down on the highway, it's a 6.2 so it doesn't accelerate anyway. It's primary a daily driver to work. I don't plan on pulling a trailer or a barn over with it so the 4.56 gears had to go anyway. The front axle going south is the perfect excuse .

 

[hatzie]

The 4.10 gears are still pretty steep for the AMG Detroit 6.xL diesels. I put 3.73 gears in my 76 and my 2000 came with them. They both tow just fine with the 6.5L diesel engines and NV4500 transmissions.
Would I do the NV4500 in the 76 again? Heck no. Gear Vendors is the less expensive way to go and you can tow in overdrive... but I have it and it works.