Xtreme Performance 5.3


Feb 25, 2021
Maricopa Arizona
This is not a G-Body related question but is related to ls's. Since there is probably more ls swapped G-Bodys than ones with factory powerplants, I figured I'd ask here.

My grandpa has an 5.3 powered 06' Sierra that he adores, recently one of the #7 lifters decided it didn't want to do lifter things anymore and took the cam with it. He just wants a fresh short/long block so it's problem free.
I've had a bit of trouble with trying to find an LM7 crate engine with factory specs. Most have higher performance parts pre-installed (understandably), but it does not need more power than stock, so the 4L60E isn't in more danger.

I did find a promising candidate from a company I've near heard of called "Xtreme Performance Automotive" for a reasonable price. They don't include specs, but also don't imply that it has more than stock power.

Has any got an engine from the company? Or ever heard of it before?


Goat Herder
Supporting Member
Dec 1, 2014
Upstate NY
Why not fix it? Every machine shop that works on anything from 2000 and newer knows how to fix that.

I’ll guess you need a set of standard lifters, a new stock oil pump, new gasket set - probably $450-500 in parts and machine shop of less than a $1k. Much cheaper than a long block. Or find a running takeout and spend the same money in parts and do it yourself.

His truck doesn’t have DOD,

This is a no brainer to me.
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Thread starter
Feb 25, 2021
Maricopa Arizona
My grandpa lives in FL and I'm in AZ, so I'm doing my best to help from 2k miles away. Otherwise I would help him and insist it be rebuilt.
I talked to him about replacing parts himself, which he's perfectly able to, but he's old and does not want to more work than swap long blocks. He'd rather pay more to know the long block is "new". Not my preferred method, but to each their own I guess.
Having a shop do it is still on the table, but most want $6-8k to do it. That'll probably be the last option.

Yes, it's a 06' gen 3 LM7 without DOD.
Last edited:


Nov 18, 2009
Saskatchewan, Truckistan
It sounds extreme!

If it needs stages or adjectives or other nonsense to sell you on it: walk away.
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