Replacement Engines?

BenK wrote:
Not saying no way...just that there is more to dropping in a larger engine.

Not up on the new ICEs, but do know a bit about swapping out for newer/bigger. Garage has a 1 ton hoist on one joist (that has two 2x8 sister'ed to it with 4x4 vertical posts at each end, so the building doesn't see any loading) that has a home made 3foot long lifting beam that allows titling the engine easily, two engine stands...one a diesel stand, etc, etc

Since the OP has air bags and wants more power...that extra power might/will kill a high mileage automatic. So that needs to be addressed.

While at that, the U-Joints should be changed to the HD if can find them

The diff, if it has the G80, might now need to be rebuilt BEFORE it blows up from the mileage and now higher power

On the tune, assume torque management will be addressed, but that is most likely boy racer and NOT good for towing heavy. That is a GREAT engine, the 6.2L, but again more car than towing heavy engine.

Why GM only has it in the half ton full sized SUV/Pickups and for now, NOT on the higher class full sized SUVs/Pickups. Duty cycle is the main reason.

On that, the 5.3L vs 6.2L will have thermal management considerations. What are the differences between a 5.3L radiator and a 6.2L radiator in a 'car'. That will be exacerbated by towing heavy. I'd go with the largest you can stuff in there...maybe one from a big block if the OP's year had that as an option. Biggest difference there is the ATF in tank cooler. It is way bigger and referred to as the 'short neck' vs small block's 'tall neck'...or 5 fin vs 7 fin, but that is mute if his year did NOT have a big block option.

Anyway, suggest the biggest external aux ATF cooler and if room, one with a built in electric fan. You can make up one yourself, as radiator electric fans are cheap these days. Pumping the additional power through a 6L6xxx automatic will generate tons of heat over what the 5.3L would. IF you have the coin, consider nitriding the gear sets, that will increase their strength

Today's ICEs are designed to run at much higher temps for efficiency, but at the cost of power mode. I like to be in power mode whenever the throttle is pushed beyond some point to WOT. The OEM tune won't allow power mode often enough for me

Bottom line...IMHO...it would cost less to just go to plan B to get a higher class rated truck

Definately agree on this, OP you really if your able to check into a gas 3/4 ton for what your pulling. All around it's built for what you need and nothing extra is needed. Now you can add some performance goodies if you want but overall a stock 3/4 ton gas will be good. Now I just added a tuner but that's me, the truck really didn't need it per say. It does act better, and surprisingly it fixed a pedal issue that I was having...but was a luxury item not a need for the truck. Anyway good luck on what your trying to accomplish. Keep us in the loop!