Starboard trans rattle/clicking

[96SR40EC]

My 96 400 EC starboard transmission is making a light rattle/knock when putting in forward but not reverse. Fluid looks good. The starboard RPMs does struggle behind when getting on plane as well. When switching to reverse all sounds fine. Suggestions?

 

[K-DUB]

if your engine is missing it will cause the trans to rattle at low rpm. That may be the rpm struggle at speed
as well. A tune up may take care of it.