A quick search on the web didn't turn up these brackets. maybe someone here knows where to get them? Dad got them in the eraly to mid 60's.
The clamp is clamped to the vertical pipe, and the horizontal pipe is slid thru the bracket. We drilled a 3/16" hole thru the bracket and horizontal pipe to keep the horizontal pipe from sliding out of the brakcet. We used 2" galvanized pipe for both the vertical and horizontal pipes.