This is inside the trailer and judging from the cake and candles, I know it was May, 1973.  Three birthdays within a week of each other.  Steph was 3, Than 2, and Jen 5.

Because space was at a premium in a 47 foot long trailer, we took the sliding doors off the closets in the end bedroom and turned the closets into beds for Than and Steph.

Gotta love those hats!