rod bearings on 1990 GMC 1500 Pickup

My #6 piston rod keeps spining its rod bearing. What could it be?

Asked by for the 1990 GMC 1500 Pickup
What do you mean it keeps spinning? I assume you replaced the crankshaft the first time around! If you didn't then there lies the problem.
1 more answer
It is probably the cam shaft if so it will need to
be pulled and have it sanded