For 47's, The 7.17 are lookin' pretty close. Considering that's the lowest ratio I can find for D60 axles...... You will REALLY need to do something about your speedo though.

 

According to the gear calculator 6.53 would be stock but might go 6.83 for a little more power. At 65 I'll be at 2856RPM the lowest great ratio for the D60 is 8 something.
I wonder how long the 1500 axles would last, each tire weighs 138lbs and can only go to a max PSI of 30

 

I wouldn't even consider 47's on 1500 axles, on a 6000 pound truck. Every little bump would likely break something.

 

When I get the 2500 axles ready I'm going to try it, just for my own curiosity

The 2500 axles are also getting ARB Air Lockers. It's ridiculous how expensive stuff is anymore.

 

Too bad you where closer to me, I have a pile of dana 60/70/80 axles (drum/disk) rear/front ends. Open and posi units. Wow your truck must be a dog with those big wheels. My 01 is slower than slow just running 32in tall wheels. My diesel ram pulling my big *** RV is faster than my 01 ram empty.

 

Where are you located at? And it's actually still pretty quick! I kept up with a 2003 Diesel which was stock. It will still burn the Rubber off the tires!

 

Calgary. I own a 2010 diesel 3500 deleted/tuned. Those dana 80 axles are pretty beefy for a gaser. Probably cost a fortune to ship.

 

The truck originally was a Cummins before I gasser swapped it. I might make a trip to you if you have a Dana 80 disc

 

I calculated my new gear ratio using the simple formula: (new tire diameter / old tire diameter (stock)) x stock gear ratio = new gear ratio. I got the following:
40s
4.73 = 4.88
47s
5.56 = 6.17

Also for the Dana 60 (which uses a crush sleeve) I am using an old school pinion (from the 80s) to eliminate the crush sleeve. In case anybody wants to do that in the future. I talked to Randys Ring and Pinion and he verified this.

I will probably go a great ratio lower to get some low end grunt.

 

Why don't you make a dana 80 drum into disk? I've done it, its pretty easy, you just have to weld on new holding plates for the disks. You running a high pinion dana 60? I would also run the 3rd brakes on the front and rear axles.