2006 Peterbilt 379 will not start

Not common. I would say more likely you have a loose connection or wires were moved near the batteries.

 

If you still have the old oil pressure switch, put it back in and try after you checked what the others have mentioned. Just because it's a cat part don't mean much anymore.

 

. Wrong thread

 

I know Peterbilt isn't anything like a Freightliner, but I drove one once (Freightliner) that had an issue like this. Turned out to be a fuse that was in the frame rail behind the cab. It had jarred itself out just a little with the fuse cover off of the fuse. I pushed the fuse back in, closed the fuse cover over the fuse and it fired right up.