5 liter SUVs and truck capability.

Correct meant gmt 800.
Either way, OP, who left the thread is talking about a 5.4, so obviously nowhere near buying a new truck.
10speed Eco has nothing to do with his question.

bid_time wrote:
If you want a Ford, go with the 3.5 ecoboost and the 10 speed transmission.

I'm impressed with mine.

If you want a Ford, go with the 3.5 ecoboost and the 10 speed transmission.

IMHO the GM 5.3L is much better than the Ford 5.4L in terms of serviceability and overall reliability. If you want a Ford go for the newer 5.0L.

The 5.3L was never available in a GMT400.
I've never towed with a 5.4 but I've never heard anyone claim they made much power. Any owner I've ever talked to claims it can't get out of it's own way.

There are about 10,000,000 5.3s and 5.4s and some are as different as apples and dog poo, so what is the question specifically?
You’re talking 2 trucks of the same era, so upgrading from a 5.3 in a GMT 400 truck to a 5.4 3v and a 6 speed would be an upgrade. If your 5.3 is gmt 800 with a 6 speed, then pick you favorite grille badge.
Both are good engines and both have their own sometimes major issues.

There are a lot of variables here that would make it hard to compare. With the 5.3, what year? Depending on the version of the engine they ranged from 285 hp. to 320 hp. Gearing is also another consideration.

I towed with two 5.4's, an 08 4sp and a 2010 6sp. Both 3.73 gears and both 145"WB F150's. Plain and simple the 5.4 is a dog. Towed two TT's, one weighing 4050 lbs loaded the other 7200 lbs loaded. Towing the loaded 4050 TT was great. Towing the 7200 lb TT was not fun. The 2010 5.4 6sp has no OD lockout so the trans is always shifting up and down. Any little rise or wind change made it shift.