1973 Formula II was made for the most part using the T7A290RX Kawasaki twin plug head, two cylinder free air race engine. Rated at 55hp which was not bad for a 290 twin back then. Some argue they made only 50 of them, some say more like 200. I think it's more likely somewhere in the middle for amount made. I wrote that article quoted in Boss Cat Legacy about a decade ago. The sleds had some potential but the USSA squashed it by putting the minimum race weight up. Cat tried to keep the clutches together by adding a reduction gear drive to the F2 and the EXT 340/440 twins as well. Most racers removed them about mid season as Arctic put out an update kit to do away with it. I guess it was not working out as intended. The bodywork is molded to get big air to the jugs and the pipes run over the hood. There were a few set up with other engines too. I've known of or seen two with the big 650 triple from the 1973 EXT. I've also been told about one found mint with the 340 RX engine in it. Since the Kawasaki twins could be swapped around or even upsized easy, a few freaks of each engine size were no doubt raced. Cat had big plans for it but with the rules changes just as the season was starting, it got shoved to the back burner and the '73 EXT and the new El-Tigre took center stage. Some say several F2 chassis were never completed and they wound up buried in some back lot. I never could confirm that one, but I did get a pretty convincing phone call about it one night. I look at this sled as Arctic Cat's Thunderjet fighter. The Sno-Jet Thunderjet 292 could be a bear to race against and this sled would have been in the same class, and probably competitive when set up right.
Anyway if you ever get a chance to hear an F2 290 run at a vintage show, give it a listen. The cackle from the open pipes and the twin carb honk will get your attention!