Andrew, I got these L.E.D.s at my LHS. They are made by Miniatronics Model 12-310-10. There are 10 in a pack and come with resistors 4-9 volts use 270r , 10-16volts use 470r resistors. The L.E.D.s are 3mm diameter. Will These locos are amazing for the price. There is nothing like them in N gauge yet. Box cars have to be assembled not like N ones that come ready to run. These HO ones are Yardmaster Series AAR 40' built in 1943-1953 so they fit the time period. Thanks Val, when I get the wiring de-bugged I will send invites to come for an operating session.