If you were desperate you could make a facsimile of the part quite easily.
Use a 1" Tee fitting then on one of the openings of the Tee put a 1" to 1/2" reducer with the "stop rim" of the reducer bored out so you could push a piece of 1/2" pipe all the way through the reducer and through the opposite opening of the Tee. Then join the Tee to a standard slip connection bulkhead. It wouldn't be as pretty but it should be functionally equivalent and reliable. Of course you wouldn't have to use 1" or 1/2" fittings and pipe, you could select what ever sizes that fit your purpose.
well 3/4 inch pipe inside 1 1/4 inch pipe leaves about the equivalent space of 1"pvc for your drain
im having a hard time finding a bulkead but look into low inlet elbows
Things are fine as they are at the minute. But any future increase in turnover would cause me real grief. It would be nice to have that option of higher turnover should i decide to go that way, so rather than wait for that obsolete bulkhead to fail I think it would be wiser for me to get all the parts necessary to change it all round. Just have a bulkhead for a drain and reroute a return line over the back of the tank.
It is indeed a strange bulkhead though.

