As per the Delaware Speedway Enduro rule book:
Small trucks allowed (ie. Ford Ranger, GM S-10 & 15 / Sanoma, Dodge Dakota, Toyota Tacoma, Small
Mazdas etc, (MUST BE APPROVED BEFORE CONSTRUCTION)

All compact and midsize trucks are allowed. If you are thinking of building something funky, they are very open to new ideas. I am building an S-10 as we speak for next season.

Does anyone know if a truck in the enduro sereies has to be a 2 door shortbox or are club cabs / long boxes allowed.

Any insigt on this would be apreciated because i am looking into building a dodge dakota for the endurto series/.

go short and load the rear with lead

i would check with wilcox before you begin any construction.  personally, i would go with the bigger cab.  trucks can be tight to begin with, let alone a midsize truck.  build the extended cab and put the roll cage as far back as possible.  i imagine that would make it easier to get in and out for a person of my stature anyway.  ;D