Is it possible to swap out my stock automatic transmission on my 08 5.4L SCrew with the newer 09 6spd automatic transmission?

I'm interested in the increased fuel economy of the newer trucks. Is there any other major contributor to the 09 getting better MPG than an 08 in the 5.4L?

I am not thinking of doing this soon. Probably when the warrenty is over I'll think about it.

I just wanted to know if it was a simple bolt and go operation, or what else would need to be changed out.

Thanks.

 

I am not positive but I think the truck's computer would need to be reprogrammed.

 

Even if it is a straight bolt in design, the new tranny still has its own computer than the '08 truck will need that to be added and the original ECU to be happy since it is no longer controlling the tranny. IF that were easy and possible, AND the tranny was free, I still don't see the benefit MPG wise for the effort. No need to tinker with it if it isn't broken.

 

What motor are you talking about? Do you have a 4.6 or 5.4? What is your gear ratio? What is your current gas mileage?
I do not believe you would see any difference in MPG with a new transmission. You may simply consider a gear change to match your driving habits. The Mrs. and I just took a trip to Toledo Bend and my truck averaged 18.9MPG for the whole trip. My highest MPG was 20.8 at 68 MPH. See my sig for details. My previous truck was a 2000 extended cab XLT with a 4.6 and a 3.08 rear gear. It was a dog and never averaged better than 17 after I swapped the factory exhaust out for a 3" SISO and upped the tire width from 245 to 265-R16.
Also I used a hypertech programmer.. While it the tuner made a huge difference in the performance, the truck was still hindered by that ridiculous gear and a total dog around town.

 

Mine is like yours: 08 150 5.4L 3.73LS SCrew, but mine is a 4wd also with a cap/shell on the 6.5' bed. Oh, mine has the stock 17' wheels also with the General America model tires.

In town I'm around 11.5-12.8 mpg. Freeways it all depends. I just took a 500 mile roundtrip all freeway. CControl set at 70, alone but with a large oak dining set in the bed and AC on the entire way [fairly flat freeway also-no passes]. I was averaging about 17.3 mpg.

I HAVE averaged 20.4 mpg on a 500 mile freeway trip also: no AC and CControl set at 60 mpg [that was a long 500 miles!].

I'm not so concerned about the top-end mpg. I was just reading about the 6spd transmission [I have problems saying 'tranny'] averaging around 14-15 for my truck around town. I'd like to get the around town up to 13.5-14.5 mpg.

Does intake/exhaust/tunes acheive this?