If you want to, you can make the small 41-46 tail lights accept two bulbs...there is an after market double bulb socket that will fit the inside of the tail light....one bulb has to be the low profile....but it works...if you go through the book of electrical parts/sockets, you might find one..
My 41 had the round after markets with the arrows built in to the covers...rusty, huge, etc....they had to go.
Good Luck.
