Q: 2008 Chrysler 300 5.7 hemi if the timing chain breaks will the valves or pistons be damaged

Your engine is an interference engine and so it is possible that the valves can hit the pistons if the timing chain breaks. Used engines can be sourced via Car-part.com or like databases. To let you know precisely of any differences in your engine, versus that used in the rear wheel drive version, I would need your VIN number. Generally, at minimum, if you are shopping for a replacement used engine you have to match the crankshaft, block, and head casting numbers. If buying from a dealer, simply use your VIN number. If you are interested in an engine replacement, YourMechanic professionals in certain locales can assist with that. Please simply inquire based on your locale. If you have further questions or concerns, do not hesitate to re-contact YourMechanic.