You should be able to tell a hydro by looking for large petals, like other then a 90's common craftsman clutch petal, anything that looks bigger then those clutch petals, is most likey petals for a hydro. Something that says "auto" or something is hydro. and if it has a side shift lever if it doesnt say 1,2,3,4,5 or sometimes 6 numbers on it for speeds, its most likey a hydro. Shifters in between the legs (nutbusters) arnt hydros.