96 K2500 14 Bolt Vent Fitting

[OO96K2500EC]

Does anyone know the size of the vent fitting that goes into the rear axle housing off-hand?
I have a 96 K2500,14 bolt open end rear.I noticed my vent hose is hanging,and the clamp's still on,and the snapped off piece appears to still be in there.
Wanted to look thru my parts drawer before I climbed under there and ordered one.
TIA

 

[OO96K2500EC]

Was roughly close to a 3/8" hole,non threaded.