Junkyard or dealer if scarce. Although used are perhaps not the ideal replacements. Great for testing though once you establish the filaments are still good. .
Nice to know there is some truth in the stories about the tail light bulbs especially.
There now should be a rush of members checking their tail light bulbs for original part numbers. . Not that there are that many cruise controls out there not functioning properly. I thought I might have had that market cornered myself.