I know this subject has come up before, but... I have an '09 H3T with the adventure package. The truck has 95k on it and it has been flawless if it does struggle in the Utah mountains. I understand that the '09 trucks were changed to take both motors. Just how hard would it be to replace the I5 with a 5.3 crate motor and what else besides exhaust, etc needs to be done?
thanks for your help

 

Man, it ll probably be better mpg and easier to just install the flexfuel kit at the dealership, make sure its the thing that has the Active Fuel Management which turns off 4 cilinders in the highway. I5 mpg wont make a difference imp, flexfuel kit will, not fot the e85 but for the AFM
GM 5.3L Liter V8 Vortec LMF Engine Info, Power, Specs, Wiki | GM Authority

 

A guy on another Hummer forum made the V8 swap recently. Might do a Google search for it.

 

Yes, Chris just made the swap. He has worked through the bugs and could provide you with lots of insight.

 

Best swap to V8 would be to sell the I5 truck, and swap it for a Alpha T. Fingers don't get dirty, and no bugs to work through.