Rear ends or just gears?

[darkroad]

First off I want to thank all of you who share the info that makes these forumns a great source of information. Here is my delima. My 1990 Suburban has a NA 6.2, turbo 400 and 4:10 gears. Left over from a previous project is a set of axles out of a M1008 Military 1 1/4 ton pickup with 5000 miles on them. I had already traded off the 4:56 gears and had picked up 4:10's and good carriers and a posi for the rear. Also had started getting together a rear disk setup for the 10.5" rear end. I mostly travel less than 50 miles at a time and only about once a year tow a car hauler with a 1994 S10 blazer from central KY to the Outer Banks of NC. Travel Interstate I64 most of the way so have several hills thru WV and Va. Am either going to change out the gears in the axles that I now have, 9.5 14 bolt rear , stock front axle to 3:73 or 3:42 or am going to finish up the dana 60 and 10.5 14 bolt with 3:73's and install them into the suburban. Already have
all new bearings and seals for both dana 60 and 10.5 14 bolt axles. Only need to change gears and finish rebuilding them. Turbo is in the works but will probably be early next year before the turbo/motor swap. Really don't want to spend the bucks for an overdrive transmission but if I do would probably get a custom built HD unit. I know this has been thrashed to death but those of you who have done these axle or gear swaps was it worth it? And what to expect as far as gas milage increases? Right now running at 65mph I get 13.6 mpg and about 13 around town. Am really leaning towards the complete axle swap with the rear disc brake setup. Both the front and rear ends now in the truck have over 200,00 on them so they are due a going thru.

Thanks

darkroad

[More Power]

Since you only tow once a year, I'd go with 3.42's (assuming a turbo) or 3.73's NA. In either case, if you have a performance 700R4, you will may need to run in 3rd while towing the load you mentioned, especially in hilly terrain.

If you towed more, I'd recommend 4.10's.

MP

[darkroad]

Thanks for the advice, thats what I've been doing with my 1/2 ton suburban, 355 vortec, 700r4 and it works out nicely but only 11 mpg and it lugs it down pretty good. Of course Ive also got 4 adults and a child and a ton of fishing gear in the back blazer. I did lose one tranny in WV at 3:30 Am due to me towing in overdrive and a crack in a trans cooler line, wasn't pretty. A 13 hour trip ended up taking 21 hours and fried my trans , could only run in 2nd gear. Had a rebuilt Gm trans installed , $2300 four years ago, plus renting a Dodge for two weeks.


Thanks

darkroad