Bowtie_Slowride

The 4.8 is bad. I never liked it anyway, did not work well for towing. I have access to an 03 Savana Van that comes with the ECM, wiring harness, 4L80E trans, engine and trans are complete. My truck is a fly by wire and the van is not so I was going to make the truck fly by cable. My concern is everything else on the truck working with the gen lll wire harness/ECM. I appreciate any and all advice and info that you can share with me. Thank you. by the way I tried to write another thread but I don't know where it is...lol I am new to this and have never posted in on of these before so I have no clue what I'm doing.

RedXray

The title and post is a little confusing but I'll take a crack at the question...

If your truck is a 2008 NNBS it's a GEN4 with a 58X crankshaft reluctor. The 03 GEN3 van has a 24X reluctor so right off you'll have compatibility issues. Lingenfelter makes a 58X engine to a 24X vehicle conversion box but no one makes a 24X engine to a 58X vehicle conversion module. You may be able to get the GEN3 PCM and harness to work with a lot of pin swapping but you'll have no gauges working on the dash.

You said the "4.3" is bad and the title says 4.8... if you have the 4.8 the easiest way would be to have a 58X reluctor pressed on the crank and use your existing harness, PCM, NNBS intake and DBW throttle body. You'll also need to swap the front covers and the and upper timing gear as GEN4 has the cam sensor in the front. The only other way would be to go with an aftermarket PCM and harness like the Terminator X and use their LCD dash for gauges.

Bowtie_Slowride

Yes it is a 4.8...sorry about that. I thought that when I put the 6.0 in with the wiring harness and the ECM that I didn't have to mess with the reluctor wheel. One of my concerns with using the gen lll harness was if anything on the dash would work or not but I couldn't get that answered. So I assume that it would be easier to just get a gen lV engine? Any thoughts about rebuilding the 4.8 into a 5.3 with just a little extra?

RedXray

I've been hotrodding since the mid 70's and I wouldn't want to go the route you're thinking. It can be done but it's going to take a lot of re-wiring the gen3 harness and it's beyond most mechanics skill level. The knock sensors are in two different places between the two gens as well as the cam sensor which they do make those conversion harnesses. This gen3 engine to gen4 truck question comes up quite a bit on this forum. I have yet to see a successful swap without the reluctor wheel swap. You'll save yourself a lot of headaches, time and money by finding a gen4 engine for the swap.

That said... if you can pick up the 03 van PCM and harness cheap they're like gold for the gen3 v6 to v8 swaps and will sell for a easy profit.

Bowtie_Slowride

I can pick up the 03 engine, trans, all together running in the vehicle now and I can have the whole thing with 81,000 for 2300.00. I think I might look into changing the reluctor wheel and swap the covers for the knock sensor and then see if it is better than finding a gen lV engine and right now they are not cheap to find especially with a 4L80E trans attached. thank you for your expertise on this, I appreciate it very much.