I was searching and came across the topic however No results were ever updated on whether the guy found a way to use GM parts , What is the best plug and play aftermarket setup

 

By far the easiest way is to add an aftermarket security alarm, and have it connected to the factory power locks. This way you use the new alarm fobs, and get added security.

 

I don't know which Savana you have, but here's a link to some stuff. I just got my '16 Express, but in upgrading the radio, I'm pleasantly surprised at how much is pre-wired, so my guess is that the harness may be there.

https://www.gmpartsdirect.com/auto-p...omponents-scat

You will need to go to the dealer to have it programmed.
Good luck. Let us know how it turns out

 

I have a feeling there is only two or three different harnesses, if any at all when it comes to the dash. The biggest problem will be the Computer Programming. The RKE, like everything else, hooks into the computer.