Parts-People offers a wide variety of MBs although most are out of stock at the moment. Go to their page here and type in your service tag number and they will confirm compatibility with your system.
I have a Dell latitude 7480 with the i5-6300u.  I see that this model came with several configurations of the sixth generation cores, and one or two of seventh generation.  Might be a dumb question, but are all 7480s compatible with all 7480 motherboards?  If I wanted to upgrade to a i7-6600, would that just drop in?
Is it possible to drop in any 7480 motherboard?