Doog said: According to Squier.com, the current Jagmasters are 24" scale, so yeah- a Jag neck would fit.
That MIGHT not be so, because of this difference.....

I just bought a Jagmaster a couple months back, one of the new 24" scale ones, and they are a bit different from the original Vista series.
The Original Vista series Jagmaster had a 24" Scale 22 Fret neck, same one used on the Mustangs, Jaguars, and Jag-Stangs.
The new ones, it seems, are the same old 25.5" Scale model's body, with a new 21 fret 24" scale neck. Which makes sense from a marketing and design standpoint (as the alternative musicians the guitar is aimed at are not exactly known for going above the 12th fret, much less the 21st), as well as that it would cost less to retool just the neck line, than retool the entire factory for a 24" scale 22 fret Japanese style Jagmaster.
The Jaguar body is also different, the Master in the "Jag-Master" comes from the Jazzmaster, which is the body shape (it's slightly different from teh Jaguar, a little wider, more stubby bass side horn). The new ones also seem to use a thinner 40mm body like the affinity series strats.
Also, the Jaguar's neck joint is a little deeper by about 2-3 mm, and the neck joins the body at the 21st fret, with the 22nd hanging a little more inward.
I'm toying with looking in depth into the differences between the different Jagmaster runs, and putting up a page or something on it, since I find them rather interesting.