From the description it's presumably not the Extra Plan conversion (AC-001). I saw various bits from it in the bottom of a box at a show; didn't try to find them all (I've got enough B-36s already), but the advert on the back of the instructions for the Extra Plan Dart-powered Mustang vac-form kit I bought at the same time claims that the NB-36H "Crusader" conversion is vac-form with resin parts. The Extra Plan logo is white letters on a black disk, The are (or were) from Poland, the address on the instructions is: ul. Zakladowa 60/5
92-402 Lodz Poland tel.: (0-42) 48-14-01 (although with a couple of Polish accents that my keyboard can't cope with thrown in). The advert also includes a Piper Enforcer, PZL P.23 Karas, Cavalier Turbo Mustang III (Dart engine) and PZL P.43 in 1:72, plus two versions of the 7TP tank in 1:35.