If that's the screw that holds the vacuum advance to the side of the distributor, I lost both of mine in Moab a couple years ago and then my advance unit fell off.....needless to say, performance suffered. After unsuccessfully searching through every screw bin at the True Value hardware, I wired the advance unit back on with baling wire and drive 800 miles home. Once at home I determined the screw to be a rather odd size, M3.5 x 8 and I had to mail-order 100 of them. This is on my '94 D90 ST. If that's the screw you need and you want a couple, PM me your mailing address and I'd be happy to drop some in the mail no charge. Better act fast, I only have 96 left.