Motorcycle Repair: 98 RK tailight removal exchange with tombstone, speed nuts, sure what size

Question
Hi, I have a 98 road king with the HD tail light, i bought a wide tombstone from custom chrome, took the lens out & realized that its fastened from the inside of the fender. I have tried every deep socket I own...cant undo them. am I missing something? what size are these tiny nuts?
the bolts from the oem HD light are placed horizontally opposed to each other, on the new light: they are vertical, I obviously will have to drill out to holes, any other tips?
thx
Vincent

Answer
Your best bet is to remove the rear tire so you can get under the bike and remove the old taillight housing.
I am not sure what size they are, but they should be either 7/16 or 1/2 inch speed nuts. Once you have the old one off you might have to drill holes for the new taillight
Good luck and happy riding
Mike