Dennis:
Here's a poor pic of a correct weight. It is a Bada MICRO. The weight marking will be on both sides of "MICRO" ie: 1.5. A larger number ie: 43 must NOT be present. This is the weight in grams and indicates a later (80's?) weight. The weight will also have raised "wings" at the outer, upper edges. These are right for probably all 60's and early 70's Chev according to Gary S. Beaupre that wrote the NCRS article. The article is over three pages in the NCRS Corvette Restorer V31, No. 3, Winter 2005 (not the Driveline as I erroneously stated in a previous post). It is excellent and you really need to get a copy if you are nutty about this level of detail. I'll bring you a weight (if I remember) when I bug you about selling the LS6 at LaHarpe like I do every year.
These weights are a lot tougher to find than Dill 627 caps but they're out there mixed in with the old weights. Tire stores everywhere will be looking for restraining orders soon.......
Installation on the backside of the rim, only, is specified in Assembly Manuals and, as Rick pointed out, was done to prevent the weights from interferring with the trim ring clips if so equipped. The weight limit, I believe, was 5 oz - then the tire rejected. Weights are always grouped ie. never one at 2 o'clock and one at 5 o'clock.
Now, I understand, the major shows will be checking lug nut torque. It must be within 2 ft/lbs or you're out!
Dave