my 96 vortec 350 is starting to knock in the lower end so i'm debating engine choices and wanted to get ya'lls opinion. here's a brief vehicle background to give some past experiences

96 gmc ecsb i love my 350 it could use a little more power but i was happy with smoking stock mustangs and lightnings. i always had tuning issues but recently found out i can fix that with a computer swap so with my current engine problems i was thinking about just rebuilding and adding a cam which i could do fairly cheap and since i found a complete rebuildable block for $75 i could build it and swap it in a weekend.

i had a 2000 z71 ecsb for a few years and was never impressed with the 5.3 that came in it. it felt underpowered and got horrible mileage compared to my 96. granted i never touched the motor or tune but honestly i think that truck might have been a lemon to begin with. kept bending rearends somehow.

i traded that truck in on a 3/4 ton 4x4 ecsb with the 6.0, loved the power on that motor but the 11.72 mpg was a wallet killer

so here's my dilemma. stay stock with some extra goodies and an easy swap, switch to a 5.3 and hope i can get it to run like my old 350 or swap in a 6.0 and try and find a tuner who can keep decent power and still have decent mileage

the truck is a 96 gmc ecsb 4l60e with 3.42 gears 275/60/15 tires currently. main goals is to have comparable or better power with more low end torque for the rare occasion i have to pull something and hopefully get better mileage. current mileage is 14.5 to 15 unloaded doesn't matter if it's city or highway

 

I can't see any reason you shouldn't be able to maintain or improve your fuel mileage with a 6.0 swap in your truck. You must remember that your 6.0 4x4 truck was a lot heavier than your 97 ECSB is; my 6.2 CCSB 4x4 with 6 gears, 3.73s, and 33s averages 15mpg on my daily commute and I see no reason you can't better that with a 6-liter in your lighter truck.

 

I averaged 16mpg driving my truck across the country without ever shutting off, even while fueling, at rest stops, or eating (my dogs were in the truck and it was July). I'm sure of I hadn't run the truck non-stop and paid more attention to efficiency I would have averaged 17 or so, conservatively.

 

I get 21-22 on the highway mods in sig

 

honestly i can't see the 03 being much heavier...maybe 500 to 750#'s more but it did have the 4l80e with 3.73 gears and 33's so my 96 had much higher gears with the 4l60e 3.42's and 28" tires. i really did like that 6.0 though especially after the dyno tune.i was there when he did it and showed me the 91 hp difference on the computer. if the encoder motor didn't burn up everytime i went to the beach i might have kept that truck but it was garanteed to spend a day at the dealership after every beach trip

darnie how's the power? i'm digging the 21-22 mpg but after my first 5.3 i'm not sure i could deal with being under powered again

 

383 shortblock with the 96 top end you already have Maybe touch the heads up of course

 

that's kinda of what i'm thinking especially since i found out i can upgrade the computer. other change i was thinking about was getting rid of that crappy vortec injection spider and go with a marine intake or edelbrock's vortec intake. i'm pretty sure i can get 400 to 450 hp pretty easy which would make my truck alittle more fun but at $1000 for the stroker kit and $500 for the new intake/injectors i'd be into for the same amount of an ls swap. i guess the first thing i need to decide is if i want to keep the truck as original as possible or mod it to death. once my jeeps done and reliable the trucks going to get a frame off resto it just needs to last long enough for me to finish the jeep

 

500+ pounds is a lot of weight when you're looking for acceleration. Think about the difference in acceleration between a 4th-gen Camaro and a Vette, or a VortecMax 1500 vs a gas 3/4-ton. I'm telling you it's VERY significant. Also, your 96 is 2wd vs your 03 2500's 4x4, correct? That also makes a difference. Your 2500's engine in your 97 ECSB would be a mean setup. I'm also pretty positive you could nail 18-20 mpg on the freeway with it; Brutal has done that with his truck (same as mine but 2wd and shorter tires).

 

you really think a 6.0 can get 18 to 20? hmm that would be interesting. i noticed everybody seems to like the lq9 but i was looking at the gen 4 engines because of the active fuel management. is the afe, vvt, and cam phasing worth the extra $1000?

i'll have to see if i can find brutal's build thread

 

BrutalSierra has a tuned 6.2 CCSB like mine but 2wd that is otherwise very close to stock. If you baby the throttle, sure I think you could get 18 highway with your gearing. Why not? I get 15mpg per tank on my commute to work with a 6.2 with more weight, more gear, and taller tires, and I know I could beat that on long highway trips. Why not?
Also, the newer engines do have more features, but only if you have the ECM to operate them. Also, most of the 6.0 and 6.2 GenIV engines only have VVT and not AFM.