If that's the one on eBay that's for sale by Parker Pawn shop in Colorado it should be from the 1950's right before they went to the guitar style peghead. I have been watching that one, too, with an idea of making a five string neck for it. The price is fair but the shipping is a deal breaker.
All we can tell is '28 to 1961 or so. 28 brackets and 4-piece flange is the only clue we have from those pictures.
But what about the decal? Ok, what about it?
It tells us nothing. If the decal was applied when the banjo was new, this is post WWII to 1961 or so when they went to 24 brackets. If made prior and went in for repair, Vega would have applied that decal before shipping it out.
The only light blue felt Vega case I ever owned was the OE for my c. 1925 Tubaphone NO 3 5 string.
My 1924 Imperial Electric had that decal and open end ball hooks introduced in the late 1920s. The decal was applied over a professionally repaired headstock break at one of the tuners leaving no doubt what happened, where and when. I had enough vintage ball end nuts to replace all 28 and those nuts from the '50s—'60s allowed me to install a complete set in great shape on my early '60s PS-5.
Gibson did the same thing to their older, plain headstock instruments. Nothing like seeing a 'teens A mandolin with a gold block letter decal from the 1960s to make you think, What the …?