Differential gearing swap question (4.56 to 3.73 possible?)

I purchased an M1031 Utility Truck, and I am wanting to get 3.73 gears for it so I can easily drive it on the highway without revving the engine. Some places say that I can use 3.73s in both diffs, and some say that I cant because of size. Not sure who to believe.

The front is a Dana 60 and the rear is a 14 bolt. Can I use 3.73's in the front and rear using the same diffs, or do I need a completely new axle?

Beans,
I have an M1028. I bought it knowing that to make it meet my needs as a freeway capable truck, I'd have to address the gearing issue - either with tall tires and a lift kit, transmission swap, or re gearing the diffs. I went with re-gearing to 3.73. I had 4WheelParts do the work. It is costly. Yes, you do need to replace the carriers too. I can now drive on the freeway with no problem, at 75. I went to a slightly larger tire size, and that combined with the re-gear gives me about 14 more MPH at the same engine RPM. Good luck!

1 vote for 4l80e

combat jump said:

Beans,
I can now drive on the freeway with no problem, at 75. I went to a slightly larger tire size, and that combined with the re-gear gives me about 14 more MPH at the same engine RPM.

Click to expand...

What size tire did you go up to? I was thinking 33, but I think I would go as high as a 35.

Beans,
I put on a set of 33's from Pep Boys. I'll have to look at them to see what the exact size is. I also started a re-gear thread a while back: http://www.steelsoldiers.com/showthread.php?62527-Re-geared-my-M1028-to-3-73&highlight=

You can change from 4.56 to 3.73 front and rear but you will need a dana 60 4.10 down carrier and the 14 bolt you will need a 4.10 down carrier also to do it to install 3.73 gears.

I looked into the same thing when I got my '08. After much fuss I decided that a 4" lift and 37" tires was the cheaper option

I did the 3.73 swap. It isn't too expensive if you get used parts and do the work yourself. Even if you just get the parts used and have some one else to the labor it isn't nearly as much as a transmission swap. I was able to do both axles for about $150 in used parts. If you pay someone to install them it is about $600- $700 per axle. Try doing a 700r4 swap for $1400, it will be much more. I have larger than stock tires and they were not enough to make me comfortable on the highway. I still don't like to push my truck much faster than 75, and I would like to get an overdrive tranny someday in the future, but for right now this works very well. It no longer feels like I'm driving a tractor.