The axles are held in place by two clips inside the third member. The clips must be removed and the axles pulled out to remove the third member. OldSub, I imagine the only thing holding your axles in is the tight fit of the wheel bearings. It might be OK to push around the yard but I wouldn't tow it on the street like that.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.