Rock Island #71 vise

[DFB]

My newest aquisition a Rock Island vise. Was pretty cheap just $40 and decent shape including the jaws though some tweaking of a bent handle is in order but in all not a big deal. Now some previous owner did weld the swivel base nut...that I will need to grind down to make it all operational again. Short of making a new bar handle for the nut (that was removed completely) I'm curious if anyone knows the original thread size may be easier to locate a retrofit part.

Any specs year dates etc will be appreciated.

 

[DFB]

Well getting the swivel base nut loose...that went much easier than expected. Just a few whacks with 2-1/2lb drilling hammer and a long handle Craftsman chisel quickly cleaned off the built up material, cold weld little penetration I guess. Some penetrating oil and few more hammer taps got the swivel base moving from it's long froze up position

Turns out the the base bolt is 1/2" x20 tpi still would like to find a nut with handle that fits correctly as the handle end cap needs to drop in flush so to clear the vise body as you turn it. Looking at some of the other vises I own the handle and nut seems to be exactly the same as what is on my REED 403

So the next thing I'm curious about is the main threaded bolt underneath holding the base and body together, at thus point I really do not need to assemble it any further but curious to any suggestions what type of tool will appropriately work on such a bolt head. Nothing in my tool drawers even looks remotely adaptable