I was tosing around the idea of changing my gears to 3.55 form the stock 3.73. has anyone tryed this? did you see any mpg increase? I do plan to tow an rv soon I don't have the tralier yet but I am looking into the 7000-8000 lbs range 5th wheel. and mabie down the road I would like to tow a boat behind the 5er. anyways would the truck still beable to tow the weight with 3.55 gears? thanks.

 

We had a 95 and a 97 w/ 3.55's. They towed that kind of weight without any issues and yes you will get better mileage. They both could easily hit 20 on the highway completely stock.

 

Or you could add an aftermarket OD unit like US Gear, or GearVender and gain a 20-22% overdrive and still have the lower gears available when your towing. Iv'e had both and the US Gear is by far the beefier unit. Barney

 

I wouldn't change the gear. Unless you are only towing very little. Barney has a good idea with the US Gear unit as I have one. My gear started at 4.11 and I tow alot. Mileage gains are only when I really use the unit or when I am empty. I usually end up towing without the unit turned on or else it starts to shift erratically.

 

well I am thinking that I will be towing 5-8 times a year probably 500-1000 miles each trip. obviously I am thinking about this to save money on fuel as we all are now a days. but I an overdrive unit at $3000 vs a gear swap for $400. now if the 3.55s will drastically heart my towing capacity then I will just leave it as is.

 

I consider going down to 3.08 as I rarely tow and wanted to up my mileage. I was quoted $500 for the swap, but I decided I better take my 18mpg and be happy I can still pull something.

FYI, now that I am driving 55mph all the time, I get 20+ on every tank.
Grandpa starts from a dead stop and 55mph has been the best thing I have done for MPG gains.

 

so do you think this will drasticaly change my towing ability?

 

I don't think it will change it at all for the weights you are talking about.

 

well that sounds good. just wounderning what would the cut off weight be? over 15,000lbs? 18,000lbs?

 

From my own experience with them in the obs I would say over 15k. We had a 5er that was 13k and it pulled just fine.

 

LOWER RPMs= more tourque on tranny.

If you change the gears that much, dont go pulling huge stuff.

 

my .02 id go for it if you are thinking about doing the swap yourself id get an old junk axle and practice taking the gears out good luck

 

I have done gear swaps before two on 8.8s and one dana 35 is the 10.50 much different than the 8.8 or is it just bigger? also do I have a 10.25 or the 10.50 and are the gears interchangeable? I have seen that people are putting 10.25 into the 10.50 is this a good practice or is it weakening the axle? thanks