I have a bad tick/knock in my 05 dodge3500 changed

Hopefully all you are hearing are poor valve lifters. As the lifters wear they will not hold oil pressure as they should and create a ticking noise as the valves open and close. With luck you can just change out the lifters and bee in good shape with the engine power too. I have seen situation where as the lifters have collapsed so the valves would not open fully causing the engine to run poorly. Being a used engine I'd run a compression test. This will give you a good feel for the condition of the engine. If the compression readings are low it will surely effect the engine's runability.
I hope this may have helped,
Tom