Your 2005 has a 7 wire connector. See the Bargman site here. I suggest you get the complete molded cord set for the best to keep water out of the plug. They do made just replacement ends, however I have not yet seen one very water tight. Some times we end up towing in the rain and you really do not want water inside that plug.
Scroll down to "7-Way Molded Connector w/ Cable - Trailer End". The part numbers start with 50-67-001 for a 6' lg and go up in length from there.
Vehicle / Trailer Wiring - Bargman
They have various lengths. Measure the one on your camper now. Find the Bargman part number then search for it on the web or a local auto parts or trailer place.
That cord ties into the junction box on the A frame header behind the battery. I'm am "fairly" sure your looks like this.
You may have a challenge getting the cover off unless your lucky. The cover if still on the original screws takes a tinny tiny Phillips screw driver and a long blade. Dirt gets into the holes and makes a heck of a time getting the screwdriver into the screw. You need to dig out the dirt 1st. I used an old drill bit by hand. Not on a power drill. A straight blade screw driver may grind it out too. Push real hard when you go to unscrew the screws or they will strip.
Once inside.... it looks like this.
BTW, I did convert my junction box cover to different screws. Those little evil Philips never went back in. Converted to stainless sheet metal screws. If this interests you I'll hunt up the size. I cannot remember if it was a no 6 x 1" or a no 8 by 1"
If you need help, and your old one will be OK to make it to the M & G in May, we can help on the install. It is what us Sunliners do for each other.
Good luck and hope this helps.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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