Has anyone swapped to from 3.73 to 3.42 with the G56 & a 5.9?

973604x4

973604x4

aka landphil
Has anyone swapped from 3.73 to 3.42 with the G56 & a 5.9?

Im tired of RPM's. I drive on the highway too much to enjoy the gearing anymore. My highway mileage can be 16 or 20 depending on speed. the 20mpg was 61mph. :badidea:

I was talkin to Bodie aka SPEEDSHIFT about this topic. He said that he can get his hands on 3.42's....somebody is making them aftermarket...but it wasn't exactly cheap. I told him to try it and let me know how much MPG's changed and he replied trying to get me to try it first :hehe:

Has anybody made this swap with a G56 and the 5.9? I can read all day about it on 6.7's but can't find much info concerning the 5.9. if its a proven ~2mpg on the highway, its probably worth the swap.....
 
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depends on how much you drive, those mud tires in your pics actually make you get less mpg, getting the rpms down will help though. have you thoughta about a gear vendors overdrive.
 
i have nitto terra grapplers now.....had pro comp xtreme a/t's.....0 mpg difference. 305/55/20.....speedo is off 1mph at 70mph.

its cheaper to swap to a 3.42 instead of gear vendors.
 
Wouldnt hurt, I had the same issue on my 06 even with 315/70's it drove me nuts, another option would be a g56 from an 08+, much lower OD. But it will probably a more expensive option.
 
Who's carrying those 3.42's?? I'll try it! Is this an option on the newer trucks?
gear vendors will cost you 4 grand when all is said and done!
 
Just search 'AAM 11.5 4:42' google works wonders. And I'm planning on swapping to the 09 g56. I got a deal in it for free. Got one off my car lot I'm gunna swap out. Can't beat that.
 
dangerous06 said:
Who's carrying those 3.42's?? I'll try it! Is this an option on the newer trucks?
gear vendors will cost you 4 grand when all is said and done!
Click to expand...

3.42 became an option with a G56 in 08 i believe...ive also read that it was only available on single wheel trucks, not duallys

thank you forrest for that reminder :bang ..............my RPM would be ~2063 at 70mph with 3.42's. I was hopin for a little less but that's still an improvement.

but i still can't decide if its worth the money....

dangerous06...give it a shot, less us know if the gear change really helps mileage in your normal driving. :Cheer:
 
Its not really worth the money, especially since you have two axles to swap gears in. I was wanting to do the swap on my '07 2wd, but at $6-800 for the swap(gears and labor) itll take a while to pay itself off. At least with a 4wd you can also go with taller tires to drop the revs, im limited with a 2wd, I dropped my rpms about 100 just going to the 305/50/20s.

I think the gear set was $450~ last I checked, for one axle. IMO get a tall narrow tire, try the 285/75/17s.
 
dangerous06...give it a shot, less us know if the gear change really helps mileage in your normal driving.

OK then if we all chip in 20. I think I can do this next week! Send your cash to my paypal account!!:Cheer:
 
973604x4 said:
Im tired of RPM's. I drive on the highway too much to enjoy the gearing anymore. My highway mileage can be 16 or 20 depending on speed. the 20mpg was 61mph. :badidea:

I was talkin to Bodie aka SPEEDSHIFT about this topic. He said that he can get his hands on 3.42's....somebody is making them aftermarket...but it wasn't exactly cheap. I told him to try it and let me know how much MPG's changed and he replied trying to get me to try it first :hehe:

Has anybody made this swap with a G56 and the 5.9? I can read all day about it on 6.7's but can't find much info concerning the 5.9. if its a proven ~2mpg on the highway, its probably worth the swap.....
Click to expand...

I was looking at the 3.42s really hard for a while, but by the time they are in the truck for both front and rear it will be about $2k, with bearing kits, gear sets, oil, and labor. This is the way I see it, the gear swap would be 2k and you would get about a 400rpm drop, a gear vendors is around $4k for 800-1000rpm drop which is great, but twice the cost and you still have a turd trans that you cant get parts for, and are not reliable under high HP. Oooooorrr you can swap in an automatic get a 400rpm drop, and build it stronger than the G56, aaaaannnd you dont have to shift gears.

Yes of course a built auto is more expensive, but for me it is a better solution, I get lower rpm for the better mileage, I make the truck way faster on the track, and I dont have to shift gears anymore which is just something I want now.
 
I have 3.42's in my 04.5. Its the best damn all around gear I've ever had in a truck. 80mph is just shy of 2k rpm in od. fuel milage is great. And I have plenty of tack left at the drags
 
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