5.7 vortec or 5.3LS?

[TreeGeared]

Consider what you want to do with the truck. Cruising, pulling, plowing, long trips, all can drive you to a different drivetrain. Personally went from a a 5.7TBI to a 6.0LS. If I was not towing so often I likely would have stayed with the TBI as it was pretty reliable. If you are concerned about fuel consumption a 4.8 or 5.3 may be a better option. I saw decent highway and modest around town mileage increases going to the 6.0, probably would have been even more with the lower displacement.

Wiring took a fair amount of time during my swap. Of course ordering a premade harness can resolve this. Then you have the tuning to run the ECU on the older vehicle. All this can add up and may drive up the price for the swap depending on how much you choose to do yourself or outsource.
Others have made very good points and I also suggest doing your own research. Make a list of parts for the different options you are considering and price them out. That may drive you in a different direction.

 

[RDF1]

If you want a 350 then go with the 350. But if I were to put the ls based truck engine in it I would go ahead and pony up for a 6.0 and 4l80.

I'm with this guy.
I've got 400,000+ miles on a few 6.0/4l80 trucks and they have all been good to me.
One had a turbo/nitrous/water meth injection on it for 330,000 trouble free miles. Lifter took out cam. So new cam bearings, cam, lifters and gaskets it's on the 520,000 mark now in another truck. Sure it smokes now but I'm not mad. It still cranks and runs fine.

My daily driver 2500hd 6.0/4l80 truck has 322,000 miles on it. Just did a fresh transmission after the stocker started having issues when cold from a worn pump with 292,000 miles on it.
Earlier this year I hauled a 40' gooseneck almost 200 miles. Lumber and trailer weighed 38,500#... factory in truck weight about 5500#.. Gross weight of 44,000# and it got 8mpg haha. Engine and trans Temps were fine the whole trip.

I do LS swaps and builds everyday for a living. 95% of them are turbo setups so it's kinda different from what your wanting.
But I have no love for the older engines. They do make great low end power but after driving several they just don't do it for me. I've tuned a few dozen of them over the years on the stock black box pcms. They feel like they do great right off idle but 3000+ rpms and they feel like they are done.
I dont have much experience in towing with a 5.3 but I've towed a many miles with tuned 6.0s and turbo 6.0s mostly well over weight.

 

[stutaeng]

I'm with this guy.
I've got 400,000+ miles on a few 6.0/4l80 trucks and they have all been good to me.
One had a turbo/nitrous/water meth injection on it for 330,000 trouble free miles. Lifter took out cam. So new cam bearings, cam, lifters and gaskets it's on the 520,000 mark now in another truck. Sure it smokes now but I'm not mad. It still cranks and runs fine.

My daily driver 2500hd 6.0/4l80 truck has 322,000 miles on it. Just did a fresh transmission after the stocker started having issues when cold from a worn pump with 292,000 miles on it.
Earlier this year I hauled a 40' gooseneck almost 200 miles. Lumber and trailer weighed 38,500#... factory in truck weight about 5500#.. Gross weight of 44,000# and it got 8mpg haha. Engine and trans Temps were fine the whole trip.

I do LS swaps and builds everyday for a living. 95% of them are turbo setups so it's kinda different from what your wanting.
But I have no love for the older engines. They do make great low end power but after driving several they just don't do it for me. I've tuned a few dozen of them over the years on the stock black box pcms. They feel like they do great right off idle but 3000+ rpms and they feel like they are done.
I dont have much experience in towing with a 5.3 but I've towed a many miles with tuned 6.0s and turbo 6.0s mostly well over weight.

@RDF1 are you the same user on performancetruck.net?

 

[L31MaxExpress]

If you are not wanting forced induction, put a nice little cam in a L31 and it will run suprisingly well. Comp XM270HR, 08-417-8 adds power everywhere in a L31 and only needs Pac1218s and Comp 787 retainers that can be installed without removing the heads. That cam comes on really strong in the lower-midrange and makes good power up to 5,500-6,000. It has been my go to on the last 3 L31s I have cammed. One of those cammes L31s went into a 2005 ECSB to replace the 4.3L it came with.

 

[HotWheelsBurban]

If you are not wanting forced induction, put a nice little cam in a L31 and it will run suprisingly well. Comp XM270HR, 08-417-8 adds power everywhere in a L31 and only needs Pac1218s and Comp 787 retainers that can be installed without removing the heads. That cam comes on really strong in the lower-midrange and makes good power up to 5,500-6,000. It has been my go to on the last 3 L31s I have cammed. One of those cammes L31s went into a 2005 ECSB to replace the 4.3L it came with.

Sounds like something I might want to do with mine, what kinda $$ are we talking about?

 

[L31MaxExpress]

Sounds like something I might want to do with mine, what kinda $$ are we talking about?

$750 give or take. That cam is $400 now. Melling 22280 would give similar results and with its slightly less aggressive ramps could get away with cheaper LS6 springs. 22280/787-16/LS6 Blue would save you ~$200. It would be a good time to install a Holley timing cover too.

 

[HotWheelsBurban]

Burb is going to need spider and gaskets in its future, and more HP is always a good idea. More usable torque too....
Gotta get em sorted out and running first! But thanks again for the tips.

 

[RDF1]

@RDF1 are you the same user on performancetruck.net?

i am

 

[OutlawDrifter]

Gross weight of 44,000#

Yikes! Hopefully you've upgraded the brakes...probably wouldn't matter with that much weight behind you anyways.

 

[L31MaxExpress]

Burb is going to need spider and gaskets in its future, and more HP is always a good idea. More usable torque too....
Gotta get em sorted out and running first! But thanks again for the tips.

No problem. I have done the spider and intake gaskets on several of them. I have ported the intake manifold on 3 of them while I had it off in my hands.

Meant to throw these up there. The XM270HR is a common uograde for the 300 hp MPI Mag Merc guys too. Really beefs up the midrange and top-end.

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Vortec Blazer had one back in the FSC days in his 350 Vortec S10 Blazer. With the 270 cam and marine intake it made 300 hp at the tires which is 100 hp increase over what he made stock. The marine intake did not add much of it. Having had an 87 GMC S15 Jimmy 4x4 always liked his truck. My 87 started with a TBI 2.8, then got a 3.1 TBI then later a 3.4 Camaro engine with FWD 3100 heads. Wish I had kept it and put a V8 into it.

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