Ron, A quick check of a 1929-46 Chevy Master Parts book shows the 1936 FB rear axle listed as GM# 601925. A one year only axle per my research. It doesn't cross over to any other axle housing that I could find. Doesn't necessarily mean a Task Force open drive differential (third member) won't bolt in, but I would say not likely.
A little snooping through some older threads in Stovebolt came across this
conversation much like yours. The last reply by Bolter Pre '68 Dave suggest using a later 1947-50 1/2ton axle mated with the Task force differential to get what you seek.
Others should be along to offer more info and suggestions.
