so you dont have the grommet? maybe you can get one from autozone in their help section of parts. you might have to cut and modify one but maye it will work. as for the two different sizes on the hose ends, my friend got creative for a school project. he took a reamer tool and reamed one end of a hose of a larger diameterwhich was a thick wall hose. then he took a hose of his smaller size and grindes down the outer wall. then he put the grounded hose end into the reamed hose end using RTV as a glue. later he said if he really thought about it he could have saved a headache by using compressor parts from the hardware store. they have reducers for compressor lines, and couplers like male to male connectors. with the two sizes of hoses put on the male ends of the connector and universal hose clamps clamped on the hose ende he could have gotten the job done. he had a street bike engine on an old go-kart frame thing he modified so you might not be able to use the compressor part method but maybe you can. have you tried the dealer for that hose you need?