Anyone know about 1974 Topps Six Million Dollar Man test cards?

[irv]

Originally Posted by Brent G.

I loved the show as a kid, and saw there are U.S. and Mexican test singles and sealed packs available on eBay. Anyone know how these cards were issued, which are rarer, and any estimated print runs?

The cards themselves are terrible, so it's easy to see why it failed, but they're weird, so I'm intrigued.

Loved that show too but had no idea these cards even existed. If I did, I most certainly likely would have purchased some if they were available to me.