Most of Joe's queries are explained fairly clearly in the ASP Buyer's Guide that's available online at
http://www.asp-net.com/bookpages/catalog_2009.html or on a handy CD that I picked up on a visit to a local cop shop here in Atlanta where I'm on a short business trip.
As for the earliest version with the red d/l indicator, my understanding was that they were discontinued because there was a fault with the locks - so perhaps the fault was, as Stan says, that they were too easy to pick.
Incidentally, the ASP "Rigid" cuffs feature quite prominently in their Buyer's Guide. It seems they're now quoting delivery for "June", but we're not told which year!
Mike Riccard
a.k.a. Mikeintightpants
Birmingham, England