I talked to jim brock about this nozzle...

he told me this was one of the first attempts at making a fine tune nozzle insert....these were made buy a company (i cant remember the name)... i guess the guy died and the company went under or vise versa..
i looked into using it on my old style place diverter, but it wont work because the actual insert would be too long and stick out hitting the reverse bucket. .....just thought id shed some light on what it is. pretty cool piece.