harmonic balancer bolt

I remember right it's 3/4 fine thread and the under head length is 2-1/4" but I can never find them in 2-1/4" long but 2-1/2" long work fine. Don't forget they have a super thick (1/4" thick?) washer under them. Gotta have it cause a regular washer will cave under the pressure required to properly torque them.