Yes indeed they are. Just check that with your headset and stem in place that the steerer tube is long enough, the Vulcan is designed around a 100mm travel fork., I recently fitted some Toras to a vulcan disc spec frame, the steerer tube was only 155mm and that was perfect, cant see a 18 inch frames head tube is gonna be that much longer. you will prob need a star nut if there isn't one in the fork already.
Defo a Reba fork then or a Tora which are guaranteed to fit??
Judging by the bewilderment, £10 may be well spent to have them fitted
Paul you are correct there mate, Reba it is then! oh and white as well 8)