we are towing a heavy trailer now and if we had too, we would swap in some 4.10 gears to replace our 3.73s. we have the LS diff, so will the new gears work with that? Will 4.10 gears hurt the already bad mileage? we are getting 13 or so not towing. ours is a 2wd w/5.4.
thanks

 

JA,

I think you'll like the extra pulling power they'll provide. In my truck it knocked about 1 mpg off the highway milage. In town driving I see no measurable difference. Of course we have different setups and you may get different results. The 4.10's will work fine with your current limited slip.

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98 F-150 XLT 4X4 ORP Super Cab Short Bed, 4.6, Auto, 4.10's, Mag-Hytec diff. cover, Magnacharger supercharger, Superchip, Gibson single cat-back, 80/100w German head lamps, Warn HS9500i winch with semi hidden mount, Wrangler dual battery kit with red & yellow top Optima batteries, Torsion bars cranked up 2.5 turns. Needs one more door.

 

I get 13.8 in comuter traffic. I get 7.6 towing 7100 trailer. You will see the engine has to work less with 4.1. I got 15 on a road trip. So I you can see the mpg impact is nill. The performance increase is great. Remember the X is pushing 6K so you need all the help you can get. I feel ford was nuts in my case with 3.55. The only time I feel the negitive of the gears is if I am pushing 80 and the rpm getting hi.

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1999 EB X 5.9 4.1 gears, Borla catback, Vortech supercharger,superchip

 

rdsii,
Do you have a 99f-150 with 4:10 gears, and did the superchip correct the speedo problem?

lutwiller@hotmail.com

 

lutwiller

I have a 99 exp. I have to find out how to modify my sinature. Ok back to your ?? no I had ford recal. I am off about 1/2 a tenth of a mile on a mile run.

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1999 EB X 5.9 4.1 gears, Borla catback, Vortech supercharger,superchip