WildBill, I use a Craftsman 5 1/2" on my main workbench. The two vises were similar in size. I took mine apart to check on swivel nut size. That swivel nut & bolt was perfect size/fit on the grandson's old Columbian vise.
Now I knew what size I needed. Then, did a google search for swivel nut for my Craftsman.
I think I got replacement from fix dot com or fixit dot com. because Sears parts was not available or out of stock.
If you can find the part number, that will be a big help.
I did wait and wait on the part, but finally arrived. It did fit grandson's vise perfectly.
swivel nut 2.jpg
I suggested to Grandson, 'If you ever trade or sell your weld truck, keep that ole Columbian Vise. It's a keeper and you can past it on to your kids or grandkids.'
That ole vise has what you want in a work/weld vise. Main screw guard, pipe jaws under main jaws and anvil. There is even a hole in anvil for a hardy.