My 5.7 litre Hemi has a cracked block and I want to find a replacement. I can still use parts from my engine. If I can't find my exact year, would an older Hemi be suitable? or would I have to go with a newer engine? Mainly concerned with emissions systems, cooling systems, fuel systems and anything else to do with the cars performance.

 

You can't go older than 03 unless you intend to go full on custom for a 60's
426 or 50's version. You can use any block from 03-08, there will just be some differences. Your 03 doesn't have EGR, but if you're just getting a short block that won't matter. 04-05 have EGR but otherwise will be plug and play for your truck, just need to plug the port if the engine still has the heads on. 06-08 1500 engines have EGR and MDS. If you leave the solenoids in you won't need to change the lifters, default mode is MDS off. It's only when the PCM sends a signal to them that they activate and collapse the lifters. If it were me I'd replace them with non-MDS lifters (requires pulling the heads) but that's just my OCD. Also if you happen to find a 2500/3500 engine, it will not have MDS and may not have EGR (I don't remember if they have EGR or not off the top of my head). You can use an LX (300, Charger, Magnum) engine, BUT a lot more differences there. They all have EGR and MDS, plus the front timing cover for the accessory drive is very different, as is the oil pan. Best bet is to find an 03-08 truck engine and go from there.