Just got off the phone with Howse. It is one of their mowers, from the 1991-1997 range. He recommended going with the gearbox and everything since disassembling it to get the shaft out will be a chore and not be that much cheaper to go without it. Plus, I'll have a one-year warranty on the whole thing.
I talked to a buddy last night that has an acetylene cutting torch, so we'll be getting the old parts off this week and painting the deck in anticipation of the new parts arriving.
Will take pictures of the progress and post when completed.