Hey guys, I have a 1999 rcsb 1500 with the 4.3 and auto. Wanting to swap in an ls. Is it an easy swap if I gather all the parts from a wrecking yard? Can i use the auto still? Thinking a 5.3, but possibly a 6.0. Thanks

 

It is not difficult if you are comfortable wrenching. You will want to get an engine with accys and wiring already matched to make life easier. Be carefull when sourcing mounts. The 4wd ones and 2wd ones are different. I was able to use my v6 computer when i did a v6 to v8 swap on my other truck just have to re flash it to your engine specs. If you get an engine with a wiring harness the same year as your truck the underhood fuse box will be compatable with the harness. I was able to use the existing transmission without any trouble. The v6 y pipe also bolted right to the v8 manifolds. Of course this would be a perfect time to do headers. The v6 radiator will work if you add a nipple to attach a hose for the cyl head vent tube. Hope this helps.

 

our 99 v6s have the old black SBC computers; you'll need a silver LS computer as well. you could get one from whoever's tuning the truck, junk yard, eGay, etc.
yep - double-check that you get the right frame mounts for the truck.
you can reuse your old PS pump & alternator, but the alternator will throw a code (can't remember which one now) & make the battery symbol come up in the DIC. it won't affect anything - just have the tuner turn that off.
eGay stainless headers - search for them. they're cheap, reliable, & way better than stock... but yes, the LS manifolds bolt right up, too.
for the extra coolant line, i just T-ed into the reservoir return line with no issues.

 

and you may as well put a cam in now while the engine's out & accessible.
if you don't, you'll just end up doing it in a couple years but have to work a lot harder at it

 

Forgot about 99 computer, thanks zebra. I would do electric fans too. Then you dont have to get a v8 fan shroud set.

 

Is a easy swap exhaust will work ur 60e will work you just need computer harness same year and a vats removal but true do a cam, headers and e-fans a stall and rebuilt ur tranny or get a 80e trust me I did the swap first and the after 2 year u did the cam and headers but I was running In a low budget so im ok but I just got a pacesetter lt headers for 140 free shipping and next is a 3200+ stall circle d but will be way easier if you do it when you do the swap try to get a dyno if you the cam headers and a good Exhaust system you will be happy

 

I would go L31 with a marine intake, long tubes, mild cam and a 4L80E if you tow.

 

thanks for the help guys, gotta call the wreckers now! There are no tuners in my area, can I get away with a hand held of some type?

 

You will need to disable vats or have the ability to plug your vin# into computer tune. If the handheld has that capability it should be ok. The route i would personally go is to get a mail order tune from one of the sponsors such as blackbear. Great people to work with. You will get much more enjoyment out of your swap imho. Cool thing is if you decide to go scan cable or in person tune later they will do for difference in price if you already bought the mail order. And if you chenge something later on they will re tune for you only pay shipping. Send them an email and see what options you have. Another thing to think about would be performing a crank re learn especially if computer is not out of same vehicleas you get your computer.

 

cool, thanks, I will check them out