Here is the DOT code on the D70-14 SS Spare.

BAK9 CU1 463

BAK9 = Manufacturer and Plant
CU1 = Compact Spare
463 = 46th week of 1973

I thought they stopped using Space Savers before the 74 model year. If so, it looks like someone replaced the tire.
Does anyone have a picture that shows the markings in a known F78-14 Space Saver? It would be interesting to see if there is a letter "D" stamped in the wheel like the one I have posted above.