[Tf175]

I actually did the measure and calculate and came up with 230 main and 68 aux., but I thought  my calculations were off as I had less than 1/4 tank in Kalispell and it only took 115 gal.  So the gauge is goofy.
Our main tank is 26x23x95 and aux is 27x10x61. Fill to 3" from top. Anyway thanks for the help, Mark

Sounds like a gauge thing , as you say . According to the book on our 86 , standard equipment fuel capacity was 203 /55 . The build sheet shows 217 /61 . There are two fuel gauges on the coach . I filled up for the first time,  with the tanks linked , held 126 gal. The gauges were indicating a tick over half before filling . After 675 miles the gauges are at roughly 5/8 . While I do not trust them , it seems that the gauges may be in the ball park based on 5.5mpg . Will know more when I refill in a couple of weeks. 
Are you pulling your stacker with the coach ?
Chris