Originally Posted by hcompton
Mounts are totally different and often require some cutting and welding to make them fit. Its not a bolt in in most cases but the trucks have a lot of room may be an easier swap. Not sure what it takes to get one in the 96 truck.
But if your going thru all the wiring and welding to make the 5.3 fit why not go with the 6.0L or 6.2L they make a lot more power and often only cost a touch more. Its also more of a performance setup for a big truck. Chevy's own choice to make the heavier trucks move.
trans will also be an issue. the LS and gen one use a different trans setup. i think its the spacing but getting the 4L80E that is often bolted to the back of the 6.0 is a great trans setup. these can handle 500+ hp in stock form. Like the th400 of the modern world trans. Alot stronger than the 700 or the 4l60.
These take a controller to run but the computer that runs the 6.0 will run them both. These are common pulls from junk yards with engine trans wiring and ecm everything including the gas pedal to make it run outside of the truck.
Another issue is the factory dash may not be happy worth he updated ecm but since the years are close should be able to make it all work with some fiddling. If you can get the full factory setup from a 2500 truck like yours with similar options may make lift a lot easier in the long run. Even if it cost a touch more its worth the money to get the 80e and all the other bits in one shot. Low miles is the next hurtle. But the junk yards all know how many miles are on there engines. But they all come with short warranty and often its easy to find them pretty much any GM junk yard will have the engine and trans combos already pulled. My local in MD used to have them in front of the parts counter. All lined up usually starting with a LS1 or LS3 moving to the truck versions. They could also fire them up sitting right in the parts area. Actually they loved to do it.
One huge mistake I see all the time is people spend piles of cash to get a good deal. A choice between getting a free motor with no manifolds and electronics or getting one fully ready to drop in that cost good money the ready to drop in motor is the deal the free motor will cost way more to get going. If you want to run carb it may be some of a deal but not the way to save money. If you want EFI then there is no other way to do it than buying it complete the wiring and ecm can be another 2 grand if you have to buy every little bit maybe more. Some of these parts are dealer and junk yard only and buying after market complete systems is not cheap by any means.
X2, what more can I say?
To the OP:
It costs a lot of money when you get into these generational changes especially if it has to SMOG. Not that it is impossible to do but the detail changes in the systems takes a lot of time and similar amounts of money to work out.
Unfortunately the injection system on the 96-2002 Gen I Vortec sucks. On the good side is the computer in those will drive the earlier injectors which means with a change to a conventional carb style manifold with injector bungs and a throttle body; the L31 can be converted back to something more like TPI. This gives a better intake than the TPI or MPFI engines with better injectors than the CSFI. The earlier injectors are now operating sequentially. This allows engine mods with various methods of reflashing or external processors, there for the sensing and drivers for the other systems are not affected and except for engine power and transmission control everything else from security to tank venting continues on as usual. These mods easily make a 400 horse 350 under L31 heads. While messing around you might want to consider a 383 kit, it's no more expensive than a standard rebuild and the difference compared to a 350 is like a different universe.