Im so confused.... I got code p1688 and i know what it is, but does the harminic balancer look like two pulleys or one?? Or can i replace it and put the old crankshaft pulley back on?? I dont know what Im buying since they are together and are called sifferent things.

 

Replaced mine back in ‘16 with ~80k miles. Had about 3 miles left before a catastrophic event.
i went with a dampened crank pulley (harmonic balancer) as opposed to the light weight crank pulley.

here it is freshly installed.

 

The factory part is two pieces that are bonded together with a rubber material. When you buy it, it is one piece. They generally fail when the rubber breaks apart and then it becomes two pieces.
So, to answer your question, it is one piece (as the photos above show). They are named different things but are essentially the same thing. Some companies do sell pulleys that are not harmonic balancers but they are not recommended as without the harmonic balancer the crank can fail or break other things inside the engine.
Look to ATI for a replacement.
ATI Super Damper

 

Right. The curious thing to me is that the lightweight pulleys cause a harmonic vibration in the engine that fails the rear main bearing. So you put a hot rod part on your car and induce a failure at the opposite end! Don’t blame the pulley. It’s bearing I’d fine.

Or maybe that pulley is to blame.😩

Peter