Thanks all. I don't drink liquor much so i was hoping to use the bottle of blended scotch i had. i broke down and bought the bourbon. Both are cheapo versions, TJ and Evan Williams, but I can see the point to the bourbon which is a bit more complex with the flavors some noted.
From 27CFR: "Bourbon whisky", "rye whisky", "wheat whisky", "malt whisky", or "rye
malt whisky" is whisky produced at not exceeding 160° proof from a
fermented mash of not less than 51 percent corn, rye, wheat, malted barley,
or malted rye grain, respectively, and stored at not more than 125° proof in
charred new oak containers; and also includes mixtures of such whiskies of
the same type.
Seems most all of us agree that bourbon is best for this glaze, but one of the other whiskies aged in the "charred new oak containers" probably would also be good.
Bourbon usually has a lot of vanilla and other "sweetish" flavorings from the oak barrels, which which makes it work well in both sweet and savory dishes. Scotch, though also aged in oak, has a peaty, smoky sharpness that doesn't mix as well.
As to the bourbon/ham connection, well they're both southern and just taste good together.
Bourbon is whiskey (from a particular region in the southern US) and generally has a different flavour profile than, say, an irish whiskey or a canadian whiskey. Just like you can have sparkling wine but unless it's from the champagne region it is not champagne.
The short answer is, you can use any whiskey but make sure you taste/smell it first. A bourbon can be deeper/heavier in the nose and taste whereas a regular old whiskey might not be. You might have to adjust with some additional herbs/spices to get the deeper tones but it will likely be fine.