Hi; I have not posted before on this site but have visited it frequently; Reason for posting, I've had it with 8.5 mpg while towing. I currently have '03' GMC slt. 8.1 /Allison, that is loaded and we (DW & I) both really like this truck. Wife has back problems and the heated seats let us drive 8-10 hrs without difficulty. We tow a mid profile 5er and last year towed for 13,000 miles out of a total mileage of 26,000. I'm currently seeking a match to our present truck with Lb7. My previous reluctance to go this way has been the injector problems i've read about on this and other forums. However, enough is enough already so as soon as we can-- New truck. I'm not new to diesels however as we previousl owned two pusher class A's, one with 225 cummins and the other 385 c-10 cat. Glad to be included in this very informative forum.