What do I need to do. 90 5.7 to old school 350.

Hey guys. Long time how's everyone? So my newest project is a 90 3/4 ton 4 wd . It has a 5.7 4l80 in it. Well the 5.7 locked up going down the rd and will not even turn over don't have a clue why .any suggestion.? I though spun a bearing, locked up timing chain, or tranny locked up.
So ultimately I know I'm putting my small block I have in it. What do I need to do for it to run ?if I keep throttle body will it bolt right to the old school 350. ? So I searched quickly and didn't find anything. I'm sure its a relatively eSy swap but do t know what I need to do for it to function properly. Thanks in. Advance.

CmOn guys. This has to be an easy one . Lol. ;)

so your saying the throttle body injected motor that was in the truck locked up on you but you have another 350 laying around. the only thing that is gonna be wired is if the other motor was carborated. if so you will have to switch out the intakes.

And knock sensors.

the older style heads have different intake bolt hole angles, but u can slot ur tbi intake holes to make it work, it should b the 4 center bolt holes, 2 on each side,put all sensors and stuff off tbi motor on the older motor, also u have use the older style flywheel, as the tbi style has a wheight on it and wheel throw of the balance of motor, if u use the 88 up flywheel it will beat the babbit outa ur mains and rod bearings,so use oler style, i think thats it

yea i forgot all about intake bolt hole angle but i thought the intake angle was only different if it was a 4 bolt main or a 2 bolt main

oh yea and what year is the old school 350 you have laying around that will be the main factor in everything

the easiest is to just get a aluminum adapter plate from summit to bolt the throttle body to the carb intake. but make sure its aluminum the steel ones warp if you snug up the throttle body bolts. swap over all the sensors and distributer and drop it in.

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Originally Posted by Ramsey

So my newest project is a 90 3/4 ton 4 wd . It has a 5.7 4l80 in it.

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What year did the 4l80 start?

Swap the heads and intake. You will pick up the benefit of the vortec style heads on the older block.

SGP93GSX the vortec heads didn't come out until 96 so there really wouldn't be any benefit to swappin the heads over the 90 model heads weren't that great.

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Originally Posted by 1994silverado

SGP93GSX the vortec heads didn't come out until 96 so there really wouldn't be any benefit to swappin the heads over the 90 model heads weren't that great.

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What? Really?

Just buy a complete GM HP crate engine. You'll have a proven performance package with no issues.