What engine will fit in my 2002 dodge ram?

The 2002 Dodge Ram has three engine options, the 3.7 l v6, 5.9 l v8, and the 4.7 l v8e. These engines have been in use through the 2001 to 2003 models, so any of the engines from these periods will work just fine in this vehicle. Finding one may be a bit of a trick though, as the engine is quite old. That said if You do find one You can likely get it cheapish, for about 800 to 1000. If You need to replace the engine in the truck, You may consider just getting a newer model. It will cost more, but it is a better long-term investment, though this of course assumes Your finances can handle it.