77 MGB rear engine mount bolt

In dealing with my drive shaft problem (see previous thread) I discovered that one of the rear engine mount bolts, which bolts the mount to the transmission, is missing. Can anyone tell me the size of this bolt?

I think they ar 5/16" x 18 threads/inch x 3/4" long. Most MGB bolts are fine thread but the ones mounting in aluminum are usually coarse thread. The easy way to be sure is to remove a bolt from the other mount and check. The hole missing the bolt may be stripped. If it is you can use a helicoil to repair it but I'm sure you will have to remove the cross member to access it.

Clifton