Mike, I don't have a 200B parts book but the 300B should be the same, lists G16605 Housing - main shaft oil seal (front).
On the other end of the shaft, V22152 Plug - expansion (1-1/2" dia.) (for rear main drive shaft w/o P.T.O.). The plug looks like the ones on your steering spindle shafts.
Service manual shows the plug installed, with sealant, in the the shaft aft oil seal housing in-lieu of the seal.