Strange (to me) S3 picture frame numbers

E-Type
1

This is on the top of the top bar of the picture frame. Also underneath the same bar and on one of the side bars of the picture frame. Numbers are raised, look like they were made with a “mini” arc. '74 Series 3, April 74 mfg date. Any idea what it means?

image

2

Could that mean 10th day fourth month?

Dennis 69 OTS

1 Like
3

10th week 1974.
Just guessing. That’s how they do it normally, think DOT dates on the tyres. Also makes more sense being in March.