The service manuals for 63 and 64 both say lamps are #57 but do not mention bayonet or wedge base. I checked other spare dashes. Most but not all 63s are bayonet, all the 64s are wedge. You can tell at a glance which base you have -- the bayonet housing is deeper. The normal replacement LED for wedge base is a T5 or T10. The T5 draws .5W and 2 CP. The T10 draws 1W and 2-4 CP.
It turns out the 64 style base is much better and the good news is you can swap out the 63 style for 64. Although the contacts
on the bases are different 63 - 64, the circuit boards are the same for both years and either base will make contact. However,
the contact points on the 64 base are much better positioned than the 63 -- the 64 has full contact, the 63 has partial. See the pictures below. Maybe that is why I have unreliable lamps in the 63 dash.
Another thing I learned about the LEDs 63 vs. 64. The bayonet base LED used for the 63 has a slightly smaller body than the original lamp. The LED does not fit securely in the 63 housing -- sometimes you have contact and it works, sometimes you don't. The 64 LED has the wedge base and it fits securely in the 64 housing. It is a much more reliable lamp.
