I talk about these in the Mag FAQ (top post in this forum).  They are the first *production* 30-rounders, and they were made during the transition from ".223"-marked mags to "5.56mm"-marked mags, so both are known to exist.  They are rare these days, and somewhat collectable, but they weren't as reliable as later USGI 30s.

[img]www.biggerhammer.net/ar15/magazines/colt_68-69_floorplate_follower.jpg[/img]

[img]www.biggerhammer.net/ar15/magazines/colt_223_floorplate_rambo.jpg[/img]

[img]www.biggerhammer.net/ar15/magazines/colt68-69_magnumber.jpg[/img]

-Troy

I would replace the spring and follower if you plan to use these mags.  The original springs were too weak and the type of plastic used for the followers didn't let the follower slide in the mag body smoothly.

Of course, these are semi-rare mags (if you're into that), so someone may want one for their collection.

-Troy

$25-40, depending on condition.  They'd need to be in new condition to get $40, usually.

-Troy