Thanks for all the input, guys!

Some thoughts on early “steel-wood” (composite) gon construction:

Drop ends on many, like PRR GR/GRA, were originally wood with steel batten and drop-frame steel reinforcement, or wood with steel sheathing.  Drop end frames were generally pressed steel framing including side post and end frame pressings, incorporating a smaller frame (actually steel plate shapes) that the drop end hinge posts fit into.  Rebuilds often got wood-lined/steel-sheathed ends with reinforcement battens running vertically.  Later rebuilds got a variety of steel ends, both plate and pressed ribs, like the P&LE gons.  B&O, strangely, got new Dreadnaught ends, but kept the weak rotating hand brake assembly, on their USRA O-27 class(es).

Sides and ends were weak, and often required reconstruction.  Sometimes portions most weak were redesigned, or reinforced, but sometimes not.  I have noticed a correlation between roads running a lot of gons, and in HD (esp steel) service, and the former, and also a move toward all-steel construction. 

Many equipped initially with drop doors had those eliminated.  PRR G24 USRA gons went from wood-lined, drop door, with weak ends, to steel-lined, no drop doors, and new ribbed ends.

Similarly, the WW2 war emergency G28, G29, G30 classes, were rapidly converted from wood-lined to steel, very shortly after the war ended.  No more wood-lined drop doors of any kind, unless in special service like electric arc electrode shipment or boxed auto parts.

Interestingly, the ATSF maintained a huge fleet of composite gons, past the end of this list, and did so successfully.  I have a GA-50 model, (IIRC) that has well-maintained wood, drop doors, and P&L, alongside the raggedy composite survivors of my eastern RR fleets.

All-in-all, an interesting study in freight car evolution by RR.

Elden Gatwood