first you can try beating the hell out of the sprocket with a brass hammer (on the teeth of the sprocket, a brass hammer won't hurt the metal but a steel one will goof it up big time), sometimes that works because the harmonics of the metals will break the corrsion loose then pry it off. if that doesnt work drill 2 holes in the front of the crank tap them and try to use a puller to get it off. if none of that works cut a diaganal slice in the sprocket then take a chisel and hammer to knock a crack in it and slide it off. i usually always order a crank sprocket when i do timing belts on z's. had 1 bite me in the ass once, where i had to cut it off. all 5 seals are the same part number so dont worry about mixing them up
