my dad's US gear od is in his old 87 chev 4x4 diesel. between the trans and transfer case.

 

No, it attaches to the rear output shaft of the Tcase and has an electronic lock out when in 4x4.

X

 

How much might it cost to switch a dually rear axle to 3.54 (or maybe even lower numerical)? I still haven't figured out what's in my C&C and I haven't driven it yet, but the truck only went 62mph with my foot to the floor, and since it was originally rollback tow truck I'm thinking the ratio in it mighty be really numerically high.

The truck itself will weigh quite a bit, probably more than I'll ever pull in the forseeable future - my trailer has a maximum GVWR of 7,000 pounds. My Ram 1500 with the 4.7 and 3.54 gears pulls it as fast as I ever need it to, although going up mountains as I often do is difficult because of where the peak power is on that engine (and that it has a really stupid electronic automatic). I'm pretty sure the torque curve of the diesel will more than take care of that.

 

I put a GV in my truck when I first bought it. They work well, but can be a little twitchy sometimes. When i installed my 5600( they fit easily) I put the gv in also(tight at fuel tank). It worked ok but was not needed because the 3-4 shift was a bit coser together. When I swapped to the different motor, it was not happy in 6th over unless I drove 85mph. I took it out and have been happy with the 6sp(3.54 dana 80 rear) ever since.

 

Prices form Randy's R&P as of 7/19/2006 when I swapped mine-

3.54 R&P - $197
D70U Install kit - $180
Extended warranty - $30
Shipping - $20.86

Grand total of $428.21

I had it installed locally for $80 plus my stock 4.10 r&p. I put it off for so long since it cost so much, but it well worth the money. I should have done it alot sooner.

 

With the amount of driving I do, saving 1mpg for a cost of $500 would pay for itself in no time. Yeah, I'll need to look into that...