I had wrote about this in another thread but I will write about it again here for history's sake.
A few years ago in the summer I travel led down to Temecula California with my '78 1300 in tow to buy some parts from Tom Young, and truthfully get some history about the Trilliums straight from the horses mouth so to speak. Needless to say Tom was a wealth of information. When Tom saw my '78 he seemed to think it may have been older because he told me that at some point in '78 they started using the same frontal interior fiberglass molds for both the bunk model and the front dinette model (they used the front dinette molds for both). This was to cut down on production costs of maintaining two molds and because the storage door on the front part of the trailer closest to the fridge
was kind of useless because it generally gets in the way (I would agree with this myself). So what they did for a bunk model was literally screw down a piece of plywood in the grooves where the table would sit when the front dinette model was in bed mode and use a long bunk cushion and the rest of the parts for the bunk bed/gaucho. Then the porta potty storage would be in the resulting space under the plywood, making it easy to pull out and return.
If you search through the threads on this forum you should find about 2 threads that talk about converting a bunk model to a front dinette model. One of them talks about cutting away the fiberglass in the front to make the space for the legs, and the other talks about removing 4 screws from the plywood and a much easier job.
Me being the difficult person I have grown into prefer t have a factory front dinette, the deluxe model, which probably means I will never own one *sigh*, and I used to think my dad was stubborn and difficult lol