2000 sierra engine and tranny swap

[chevroletman223]

Ive got a 2000 sierra short step 4x4. it has a 4.3l and a nv3500 5spd, i absolutely love the truck and dont want to get rid of it as its paid for and i love the looks of it, but id like to have a little more power and as i get older im getting tired of shifting. So i was thinking of dropping in a 5.3l and a auto trans from a donor truck at the local scrapyard thats got really cheap engines ($100). Does anyone know the extensiveness to this swap? i know id need the engine and its accesories, the trans, the transfer case, the engine wiring harness, steering column, gauges, engine mounts, radiator, computer, and i plan on putting electric fans and custom exhaust in. Is there anything else? if i convert to an automatic can i still use my under dash wiring harness? driveshaft? will there be any problems with bolting an auto tranny and transfer case up to my frame? Thanks for any and all help guys, i already know its a big job and ive definatly got the ability to do it, ive built countless cars and engines. Just need to know the extensiveness.

[Alderson95]

Ur best bet is to keep the the standerd trans. Because the 4l80e and 4l60e for these years are so complex with the trans computers that are requierd to move them . U can do a raw trans swap. That mean no computers no wires. Also if u put in an automatic u will have to more than likly have to get a new drive shaft or shorten ur stock one. As far as the motor goes the 4.8l 5.3l and 6.0l are vertual identical. I have helped my freind chris put a 6.0l in his 02 tahoe. The only thing we did was change the fule pump to a 65psi pump. But if u realy want an auto trans best bet is find a truck cab just like urs that is setup with auto trans and swap them. O and 4.8 5.3 and 6.0 same pully system as far as i know
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[chevroletman223]

Thanks for the reply, thats what i planned on doing was finding a truck with the 60 or 80 that i could get the whole setup from. the junkyards got a few of them. i guess my main question and biggest question is, would i have to change the under dash harness? i wouldnt think so but i dont know for sure... If anyone can shed some light on that, id greatly appreciate it. thanks again for your response, its appreciated.

[chevroletman223]

Nobody has any idea if the dash harness is the same?

[truckdude239]

i doubt it

[biggsteve97]

The dash harness will be the same. However the PRNDL window will not work unless you reprogram the cluster to let it know its in a vehicle equipped with an automatic. Of course you will have to reprogram the pcm for the new engine/trans combination. The transfer case should bolt up just fine the only concern would be the number of splines on the input would need to match the new trans and some are the same. You may have to drill new mounting holes for the trans crossmember only if the new trans/transfercase combo is of odd length. your rear driveshaft will need to be modified and possibly the front/ depends on the amount of available slip in the yoke. good luck

[usmcchevy]

It is a lot of work, you will need the engine with all of the accessories and engine harness.

http://www.ls1truck.com/forums/v8-co...wap-guide.html

[chevroletman223]

okay i figured herness was the sa hanks guys! aldron,about reprogramming the cluster.... i have a complet 5.3 with all accessories and pcm, trans, transfer case, wiring harness.. etc... now for the question, will i have to change out the cluster? or will the new pcm make the cluster show the prndl? thanks again

[mcfarlnd]

I would just plug the old cluster in and see if it pans out. In your tune there is an option to select a manual or auto trans. I wouldn't buy a new cluster unless you had to. Try to see if it will work when you get there.. Got a long ways before you worry about the selector. Most of the stuff for these trucks were very interchangable. Just let us know if it works.
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