A little progress. The fuel tank is the same shape as my Mayhem but it is rotated 90 degrees... I don't know what Sig was thinking. The curve should be down so you get the last of the fuel centered in the tank for as long a flight as possible, go figure. Anyway I made my own little retainer for the tank and here it is. The engine mounting holes have been drilled using a 46AX as a template for the 55.