Trying to save my 98 cutlass

I am almost at my end with this car...but i am willing to invest a bit more if it means getting this car running....so i have a 98 Cutlass V-6 and the original engine died at about 155K think i threw a rod or broke a piston thing clank n clunk so bad.

So i put a new-used 99 engine in it and it had all the same problems that the old engine had...so i fixed everything that was wrong on the old engine. So the only problem i have is this Tapping on the passenger side of the engine. it does while idle and when driving..

So the question is what could be causing this tapping are these engine known for having this problem. i have had two engines and both have this tapping problem. I am thinking it could be the Push Rods, lifters or the rocker arms but i want to know if there are any test i can do to narrow it down....PLEASE HELP :banghead:
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A quick and easy test is to run the engine with the accessory drive belt off to eliminate a noisey accessory, i.e. a belt tensioner or a/c compressor esp. if they were swapped to the replacement engine.

I know that's not the case B/C i took all that stuff off the old engine...and it was new stuff every pulley and the belt... the knocking is def. inside the engine.