They do not have the rectangular washer. I've never seen studs on the transmission to attach the mount, but I've always been into 73 down "A" bodies.Well there are two of them. I was wondering if it was part of the braces on each side of the block to trans.
I am going to say its a transmission mount bolt for a 4 speed. I only say that because most autos I have ever seen have studs on the trans and take a nut and rectangle washer to attach the mount. I have never seen a 4 speed with studs but only the bolt here^^^ Xs2 not to say someone can remove the studs from the auto and substitute bolts but I don't think that is the correct way.
Rear trans mount bolt and washer