Bernard, I guess I shouldn't have said derate. 102 had Pratt and Whitney R-1830-90 engines, which were originally equipped with 2-stage superchargers. The extra boost wasn't needed in civilian applications, and also had a tendency to crack cylinders, so an airworthiness directive was issued by the FAA to deactivate the high blower setting. The engines were still rated at 1200 HP at sea level, but this could vary widely depending on field elevation, temperature and condition of the engine.
All the hydraulic things that motivate a Gooney are located behind the copilot's seat. These include the hydraulic reservoir, the distribution, shutoff and pressure relief valves, and all the plumbing that goes with it. On many DC-3's and C-47's, especially those that carried passengers or were used as VIP transports, the hydraulics were usually covered with some type of trim panel. On the military and cargo airplanes, it's all out in the open in full 5606 (the mil spec number for the hydraulic fluid, which is red) coated glory for everyone to see.
102's hydraulic innards were in full view, so I decided to duplicate them, as they can be seen through the open cockpit windows. The original idea was to scratchbuild the whole lot, but while rummaging through the junkbox, I found a piece of an engine from some long forgotten model that looked remarkably like what I wanted it to, so after a bit of cutting, piecing cleanup and some repainting, I got the result seen here. It's not totally accurate by any means, but it does convey the look I wanted and it's pretty close to what the real thing would look like viewed standing outside the airplane looking in. A small piece of clear sprue to simulate the quantity sight glass finished it off.
I wasn't happy with the original part I found for the jumpseat (a little flat and two dimensional), so some more rummaging came up with something a bit better. I cut the back off the original seat, grafting it to the new one to get the headrest. One of the kit radio boxes was hacked off and made into the seat base. Last touch was to use another of the kit radios to replicate the avionics rack on the right side by the cockpit door. The mock up is seen in the photo. Since 102 served in both the Army Air Corps and the USAF, the interior colors were a mix of both, with the floor being somewhat interior green where the paint wasn't worn away by forty years of traffic, and the rest of the cockpit in dark gull gray. The cargo compartment will be in bare metal, but this model will have the cargo doors closed, so no further work will be done there, mainly because there's really nothing in there to see!
1 attached image. Click to enlarge.