Need opinion on KW T660

I was reading your post whether to keep your older truck or get another one....I WAS in your shoes a few years back and decided to keep my older truck. I'm glad I did. Engine is now completely overhauled, transmission rebuilt, new rear ends, new tires, tie rod ends, king pins replaced, etc.
My truck runs soooo smooth and I know every nut and bolt on her. No surprises.

Sort of like breaking in a new baseball glove. I prefer the older familiar one!

 

I have been driving a new fleet spec T660 with a ISX 450 and a 10 speed. I do not know the rear end ratio. I have been averaging 7.2 mpg at 75,000 pounds. Somedays I get better, up to 7.8 mpg but never below 7 mpg. The truck is governed at 62 mph. The biggest thing that will kill your fuel mileage is the trailer gap between truck and trailer. Mine is set at 41 inches. The question is do you want to add another fluid to your truck eveytime you fuel up?

 

From what I see the T700 with isx, is the same price.
Have you considered it?

 

am getting a solid 5mpg with ours, but we had some engine issues. we got 8.5 with mt trl after fixing, will update soon as to longterm mpg. just got it fixed this week. it is a 2011 t660 with a 2010 cat c15 475 hp, no idea what gears are in rear. but we get better milage at 68 than 60. figure that one out... and going 77 i am only at 1420 rpms... seems like we have tall gears, but no one can tell me exactly.

 

My 2003 with 475 isx had the last time it was read had a life to date 7.13 mpg

 

LOOK on the drivers door.