Thanks elie, great suggestion. The top of the tyre to underside of wing is 150 mm and axle bracing to outlet pipe is 157 mm. For reference my tyres are 185/70R13. I also measured the shock absorber stem length between the top of the cylinder and the bump stop which comes in close to 110 mm which I think is the max the axle could actually travel so I'm going to be fine with the 73037 fuel tank. Thanks Paul.