I'm not exactly sure how the bulb numbering works ... both 7440 and 3156 are also called T20 bulbs (what I have), but 3156s and 7440s are, to my knowledge, not interchangeable.
It's waaay too late to be messing with my brain like that. I'm pretty sure that didn't make any sense, though.
I may have to just order some and see if they fit.
I wonder if they would survive DRL usage any better than LED's?