just wondering which is better and which one gets better mileage and how to tell the difference

 

2004.5-2005 trucks are the LLY
2006-2007 are the LBZ

8th digit on the vin
Vin code 2 = LLY
Vin code D = LBZ

My LBZ got 13-17mpg stock

 

Ditto. I think the LLY trucks got slightly better mileage stock, but a tuned LBZ will do pretty good, and they have less problems.

 

Not rippin on duramaxes but went and test drove a 2004 ext cab sb, and it seemed really poochy. The truck that i have now is a 1997 f250 ccsb powerstroke 5 spd that i thought about trading on it, but i really dont want something with less power. By the way the duramax had 97,000 in awesome shape and my truck has 180,000, both stock trucks but mine would stomp that thing believe it or not.

 

Even the stock LB7's I drove had a good amount of pull to them

 

something doesnt sound right about that an LLY is 310hp 600tq stock, your 7.3 is only in the 230hp 450tq range

theres no way that the LLY should be doggy compared to your 7.3
I know my LBZ is a rocket stock, even nastier tuned

 

Im thinkin the same thing.

 

Externally, didn't the badging on the door change from red to blue for the '06 with LBZ?

 

on the 2006 and up the badge on the side says Duramax/Allison

2001-2005 the door badge is just Duramax Diesel