55-2nd series fuel tank bolts -what's correct?

[ndamerau]

I took the fuel tank out of my 55-2nd series 10 years ago and I am ready to reinstall it (get out of my way, I am moving fast). The bolts that I removed were obviously not original; they had loose nuts under the cab. The holes have nuts welded to the cab underneath, but the holes are stripped/drilled smooth, so I can't tell if the bolts are supposed to be 3/8-inch or 5/16-inch.

Anyone out there know or have a picture of what is supposed to hold the straps down? This truck is almost all original, so I am trying to keep it that way.

[Jebb1978]

Oh man, I have no idea what mine looks like off the top of my head. I can take pics if no one else has on my next day off. That will be Friday.

[Bad4wd]

5/16'', just tap mine after paint.

[5Mike7]

Yes, 5/16th-coarse, the original bolts have the "washer" made onto them, not sure exactly what they are called, but you probably know what I'm talking about.