90 sierra rcsb ls swap

[hotrod]

Hey everyone, about to do my ls swap, I just got a 5.3 motor and tranny complete from an 05 silverado last week at a good price.

I will be starting my wiring harness soon and had a couple of questions.

1. If i've been reading right the only thing I keep from the old harness would be oil pressure and water pressure and a/c?

2. Since my sierra has the moonie style gauges, how does the speedometer get wired in for the new harness to control the speedometer that's in my truck now?

3. The ses light, does the new harness get spliced in to the wire coming from the sierra pcm? I don't think I really found a definite answer on that from reading around online. Could someone explain how to use the ses light that's already in the dash?

One more thing, do I really need the oil pressure and water sensor adapter or can I get by without adapters using the sensors from my 350 tbi? Wrong size thread i'm guessing is why people use the adapters?

I will try to get as much pics as I can, hopefully some video too.