I recently finished my Yukon Denali I added a 6" lift 35"s I want to change my gears to etiwgr 4:88 or 4:56 can anyone give me a few suggestions about the good or the bad for each? I do and will continue to tow and its highway driven when towing. Also what size gears do I need 10 bolt and 8.5? Do I need a new carrier for the front what's a good posi for the rear being my oem has 168k

 

I run 33" tires with a 4.56 gear, but I also have a 5.3. Since your on the highway quite a bit and have a 6.0, I would go with a 4.56. 4.88 will perform a little better, but the rpms are gonna be high for highway use. The 6.0 will make up for the difference in gear IMO. Look into either an Eaton posi (not the gactory G80) or a Tru-trac. Personally I run a Tru-trac and I like it.

 

What rpms do you turn around the 70mph range? Majority of my driving is in town too forgot to add that

 

35's @ 70MPH you will turn 2500 rpm with 4.88 with 4.56 you will turn around 2200 2250 @ 70mph.

 

around 2400 @ 70
with 33s and 4.56s

 

Seems like 4:88 will be worth it just for the low end benefit and off roading I also do a lot of camping and beach riding so a lot of low end is desired. 2500 at 70 isn't too terrible I guess.

 

I don't think it is, Just change your oil a little sooner and all will be well. I went from the stocks 3.73 to 4.56 now 4.88. I like the 4.88 but I'm building a 6.0 and did the 80e swap so it should be pretty peepie down low.

Look up Ron's machine on here. he is a awesome guy to buy gears from and his prices are pretty good also.

 

Thanks so hows the bottom end with 488

 

it was ummmm,awesome. I could mash it and it would roast he 35's. if I had 20 more HP it would have broke loose at 1-2 shift or felt like it would have anyways. That was with a semi modded 5.3. Now I'm going with a fairly well built 6.0 I hope it has some show'nough grunt down lo, I'm also doing a 3000 stall for the 4L80e. I hope its a beast..

 

since your a 4speed, best would be 4.88's since you tow. its basically like 4.10's on a stock height tire truck. between the 4.56's and 4.88's only difference rpm wise is maybe 200. little better acceleration for 200rpm since you tow its worth it.