So I posted a few different places but figured since this one is more directed at these motors maybe somebody here will have some knowledge. Long story short I have a 2007.5 LMM fully deleted. The motor had some piston issues so I got a motor from an ambulance van lmm with under 100,000. Everything was swapped over by the mechanic that needed to be change such as the intake engine mounts harness stuff and what not. The problem is nobody can get it to run since it’s been installed. The tech to as well as a manual gauge is saying zero oil pressure. They pull the oil pan didn’t find anything unusual except the oil didn’t make it to the filter or anything. The oil pump was checked after removing the front cover and everything seems perfectly fine. In fact the oil pump and sending unit both look new. I’m basically looking for some suggestions or knowledge on what the problem could be. This truck has been down since December no one seems to be able to figure out what’s going on with it and I’m starting to think it’s done for. Someone told me that they believe the system needed to be primed but it was a used motor. Like I said at this point I’m looking for any type of input as to why a motor would not run that ran one pulled. I appreciate any and all responses