Twist-in bulbs for instrument panel

OP I am wondering if you are confused.......what you pictured is the bulb in the socket--two different pieces. The bulbs listings are in the manual "somewhere."

Go to MyMopar and download a 65 Plymouth manual, free. Bulbs listings are in the rear of the manual under "specifications." According to the chart the oil lamp is a 158 which is not a twist in, rather a baseless "push in" known as a "wedge" base