I am planning to trade my tow for a Duramex/Allison,2wd,EC,Long bed,2001-2003 to pull a 5er 12000LBS all over North America 5-6 months every summer.
Need some clearafications and assistance please:(so here are some basic ones)
A.What is the differance between LB7 and LLY?
B.From which year GM has Duramex/Allison combo?
C.Are there different engines in Duramex models (I mean in the same year different engine 6.5L/6.2L or each engine comes in different year).
D.Are there different Ratio ?
C Is there anything I have avoid .
E.What are the main differences between GM and Chevy?
What would be in your opinnion the best combo Duramex/Allison in the range 2001-2003 regarding engine/ratio(without any upgrading and chips) for my rv life style.
Thank you very much.

A. the LB7 motor was put in the trucks from 2001-2004.5. The power rating on the LB7 is 300hp 520lbs of torque. Starting in 2004.5 they came out with the LLY which is an updated version of the LB7 making 310 hp and 590lb of torque with the allison trans, the manual trans remained at 300/520.

B. 2001-2005 is the Duramax/Allison combo

C. No, they are all 6.6L motors, only difference being the LB7 vs LLY

D. No they are all the same gearing

E. I am guessing you mean GMC and Chevy, its only in the styling of the vehicle, drivetrain is the same

Have you thought about going with a dually since you will be on the road a lot? The dually is much more stable. As for power, obviously the LLY has more. I would suggest having a vin check here with whatever vehicle you look at. Some of the 01-02's have more injector problems.