Wilton C3 vises questions and info ask.

[WE3ZS]

I hope this is the right place to post these C3 questions.
I have these 2 Wilton C3 vises, which I think are different ages based on some minor differences. I am looking for any help that could date them and any other info on them. Both are still very dirty from the heavy industrial machine shop they came from, both show a little wear and tear but not too bad, both have one (of 4) bolt down flanges on the swivel bases broken off and one has a modified handle where one end is threaded with a nut.
Here are some pictures of the one I think may be older.

 

[WE3ZS]

And here are some pics of the other newer (?) one.

 

[WE3ZS]

I really don’t know much about vises in general, but I do know that the Wilton bullet vises have a good reputation and are considered to be among the better units. And these monsters are freaking heavy! They have to weigh about 200lbs each!
So is there something in these pictures that could suggest an age or any other significant info on these vises. Is one considered better than the other based on the difference between them or their condition? I don’t see myself ever needing 2 of these big vises, what would be a fair ballpark value of these?

 

[exmaxima1]

the date is stamped on the bottom of the slide on the slot key

 

[WE3ZS]

Thank you, I will give the slot keys a look. Is it a standard date format or is there a code to it?

 

[Shiftless]

Thank you, I will give the slot keys a look. Is it a standard date format or is there a code to it?

Easy code
example:
6-91 means June 1991

 

[WE3ZS]

Thank you, I don’t think that they are really old old, just curious what exactly I have here.

 

[Shiftless]

Thank you, I don’t think that they are really old old, just curious what exactly I have here.

I agree
Probably less than 25 years old.
I have a small collection of Wilton vises in the various sizes and quite a few by other manufacturers. My “user” vise is a Wilton C1. Great vise!