Forget about redline..........If you have 4.10's you are going to run 2800 rpm's at 80 mph. I have 3.73's and at 80 mph I am at 2400 rpm's. That is with stock tires.

 

Speakle- Thanks for the link, I just sent them an email to confirm the G56 only getting 3.73 rear ends.

 

I think that 3.73 was the only thing available with the 6-speed. If it helps, I know mine is 3.73 and I hit the same rpm range you mention at 70.

 

You should have asked for the build sheet on your truck, its cool to have so you can see everything you have on your truck and it would have answered your current question as well.

 

I asked them a couple questions, and for the build sheet. Thanks dude.

 

if you have the G56, then the only option you have are 3.73's due to gearing. this change happened in 05.5 for the most part. if you have an 05.4 and later then you have the NV5600. from the lower gearing you could get 4.10's with it.

I personaly believe 3.73's is the highest these trucks need. 3.54's you be perfect for both auto and stick.

 

Drew - If reverse is to the left and then back, does that meen that I have a G56 ?

 

next to 2nd, yea. all truck built after Jan 05 have the G56.

my reverse is next to 5th, NV5600.

 

The dealership may not have lied to you knowingly, they're probably just ignorant about their trucks. When we picked up my fathers new truck this week, the salesman said it didn't have a warmup wait time for the engines anymore, the mirrors power fold out, and the truck was getting 22MPG (the overheadwas on metric, it was actually 11MPG). I don't think he was trying to lie to us since I drove up in my 3500 to look at it.

 

Thats the problem with dealers, half of the salesmen are generally so stupid you dont know if they just have no clue.