Don't worry, found one. There is this thing on the internet called "Craig's List" and people post all sorts of stuff on there! Who knew?!
That being said, it appears that the interior trim pieces are different for partitioned and non-partitioned PMs. Luckily I found a local PM owner that just wants to do a straight swap. Best. Price. Ever.
I'd think about airflow before totally sealing it off. The exit vents for the HVAC (vents) are located in the back of the cargo area. If you totally seal off the cab, the fresh air entering the cab has no where to go so you will compromise the efficiency of the heating/cooling....
That seems weird as a factory installed partition completely seals off the back area.
That being said, I found one locally (for $150!) and with a little modification to the interior trim pieces I got it to fit like a glove. It is AMAZING how quiet it is now (especially since I have a lot of tools back there.) It heats up the cab WAY quicker now. It has a slider too.