+1AGXs were originally GAB shocks manufactured under licence for the North American market. For many years, Kayaba Europe could not supply these shocks to UK consumers. The original AGXs sold in the UK came in via Flyin Miata, and were not covered by a KYB warranty.
In Japan, a lot of aftermarket shocks sold are revalved KYBs. The adjustble KYBs sold in Japan were not the same as AGXs (though in the last couple of years, the range has been rationalised).
Interesting find... ask the seller to measure the shock body length. KYB makes both stock length shocks and short-body shocks for the NA. If it's the short body version it might be worthwhile....stumbled accross these on ebay, these just rebadged agx's??