65/66 Dart Tail Lamp Bulb?

Yes, 1095 is the one and only correct bulb for this application. 1073 will fit, but is multiple times too bright.

1095: 4 candlepower
1034 or 1157 dim (tail) mode: 3 candlepower
1034 or 1157 bright (brake) mode: 32 candlepower
1073 or 1156: 32 candlepower

Looks like this outfit has 1095s in stock, and there are old-stock/surplus finds to be found, like this. Otherwise, about the closest you're going to get in a current-production, easily-found bulb is an R5W (4 candlepower, filament located closer to base than in the 1095…might or might not have a large effect on the lit appearance of the lamp).