As far as leg levelers, for stern the front legs had the short level
(2"or 1 1/2") and the back had the 3" leveler.

Those legs are Bally, not Stern.

Pinball legs 101
Bally, black pointy end (2 lengths, one is 1/2" shorter than the other)
Gottlieb, eggshaped end ( 2 lengths 26" to 32")
Williams, slightly cut off end ( common 28 1/2" older 31" or so)
Stern, slightly cut off end hammer-toned finish. ( 28 1/2" )

Stern measure 28 1/2"; true for that period of time.
What about the picture of the bottom end of the legs?????????
you only show pictures of where the leg bolts screw in?
Take a picture of where the leg levers screw in, PERIOD!

Note: The pinball manufacturers used the same
----- parts manufacturers to make most of there
----- parts. However, they had to, by law,(I believe)
----- deviate there parts by 15%. So, each manufacturer
----- has their own I.D. Yes, they shared same parts back
----- in the 1050's and 1960's they shared copyrights.
----- Bally and Stern shared the same CPU development
----- in order to save cost. But the boards themselves are
----- fiscally deferent.

It will tell you the manufacture. As I have noted
above.