why does my truck smoke never did before i put the new parts on

you may have coolant leaking into the combustion chambers. most often because of a bad head gasket, less often by a cracked block. you can do a combustion leak test yourself by getting a kit from the auto parts store. there are a number of good youtube vids on how to do this. or you could take it to an emissions shop or reputable mechanic and they have a sniffer for the exhaust and they can tell you if it is this kind of leak.

It probably needs to go to a good diesel mechanic. If you had it overheat it may be very expensive.