On my log splitter I need the gear on the shaft leaving the engine going to the hyd pump

Hi,
Do you refer to the hydraulic coupling? Kinda looks gear-like though it is three pieces not counting the two set screws or keys. Try looking at this page from the Northern Tool website:
Hydraulic Half Couplings | Hydraulic Couplings: Flush-Face, Half, Hose + Pipe Hydraulic Couplings | Hydraulics | Northern Tool + Equipment
Peace,
Clarke