Mustang Boards - steeda underdrive pulleys

hey guys I have a 98 GT and just picked up a used set of steeda up and the guy didn't have the bolt and washer for the crankshaft pulley. I have an aftermarket balancer on there due to the fact the original one started coming apart. was wondering if anyone knew offhand of what size that is supposed to be used so I could get them before I do the install. also would like to hear from other 98 GT owners on how affective they are. have heard numerous stuff both ways. the motor is still stock with the exception of a cai. thanks for the help and insight