surfacing help

I have been working on this model for fun and have been having trouble tieing up the rear end. i have tried to put in place as much or the geometry that defines the shape a possible but i cant get it all to come together, if one of our resident rhino experts can helpme tie up the back i would be gratefull.

here is the file all zipped up

Sorry I don't have time to get in depth with this right now, but just looking at the attached jpg, I would suggest that before you apply fillets, you join your model. Check for and resolve any naked edges, than use the FilletEdge command.

Dan