This picture shows a 40 foot Case IH flex draper on a 27 foot wheelbase wagon. Model year 2014 and earlier for 35, 40 and 45 foot will be the same.
There are a few flex draper heads - notably Case IH and New Holland 35, 40 and 45 foot units (up to and including model year 2014) where the gauge wheels interfere with the carrier wheels. With the shortened wheelbase the right hand gauge wheel will fit between the rear carrier wheel and the light bracket with the head almost centered on the carrier. The gauge wheels should be in the fully raised position as well as the universal pads.
The gauge wheel position on the 35 foot units will be changed a total of 5 feet narrower for the 2015 model year. These heads will no longer fit on the 27' wheelbase and will require the 30' wheelbase.