Is it a 1500? If so it uses MDS and should be replaced with an MDS eqquiped engine. If it is heavier truck it has no MDS and can be replaced with either, if your replacement has MDS in it leave the solenoids in and not connected to anything or buy the special MDS hole plugs I sell but they are not needed if you just want to leave the solenoid in. Like was mentioned any long block from a car or truck will work as long as you follow the rules I mentioned. Cars have different oil pans, exhaust manifolds, intake manifolds and timing cover/accessory drive set ups. Also a 6.1 long block bolts in also and they are getting more affordable. No reflash or anything needed unless you put a NON MDS engine into one that came with MDS, in that case a flash can remove the check engine light code.