Possibly, there are differences from '04 to '05--when they changed from electric slide operation to hydraulic.
On my '05--the outlets in the door side (large) slide are connected in a junction box at the rear of the slide and on the trailer frame. It is the same size as a single wall switch box with a metal cover on it. I can't feature it not being there, but...
Same thing goes for the off-door (kitchen) slide but at the front with more wiring and TWO of the single junction boxes.
Both slides have the wires supported by a plastic carrier that is connected to the frame and the slide.
Again, mine is an '05 and may be different. Some of the wiring is run under the floor area along and inside the frame. At some point, you will probably have to begin removing the underbelly cover to access areas that the wires run along. All of this is a learning curve gone thru by most owners at some time. This will be a good time to look at the insulation and replace it as, over the years it may have gotten water-soaked or had some rodents living in it--or maybe it is in good shape. Whatever, taking down some of the underbelly cover (plastic, it can be cut and taped back into place) will allow you to inspect parts of the trailer some people never check. Wear safety glasses as there will be rust/dust/screws/sawdust/etc to fall down that were left there in the assembly process.
I know this is annoying to you, but have patience and keep at it.
And, all of the above assumes you have a 3-slide, 36' unit. Most back then were 36TK3s, or 36CK3s. They were also making 32 and 34 ft models.
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired