Bench seat bolts, difference

[General23cmp]

Originally Posted by 71CHEVYSHORTBED402

My 1971 takes (GR 5) 1/2" (wrench) recessed hex tapered bolts with spin washers top and bottom. The bolt threads are 5/16-18 x 7/8. I always measure from the spin washer. The bolts are stamped "RBM".

Are the dimensions above for the bolts to the brackets to seat frame? This sounds like the size I have.

I definitely do not have 3 sizes of bolts as some have said they have. I have two sets of 8, and except the pointed ends on one set, they are essentially the same bolts. There is a chance that the second set of 8 is from another frame to seat rail set I had before, and perhaps I don’t have the rail to cab floor bolts on me. Are these all the same size thread/bolt diameter to go from seat to rail and rail to cab, or is one a bigger diameter bolt?