Well, after 4 nights of camping and copious amounts of service roads and 4-lo, it sounds like there are marbles in the bell housing of my 5-speed in idle and each gear but 4th. 247k on this one, so I guess it was bound to happen at some point.
Still shifts normally, but it'll be sitting in the driveway until I can figure something out.
Anyone have any luck installing a used transmission? There's a good junkyard down in Denver that has r150f's in stock, but I'm not sure if I should spring for a rebuilt one (or try rebuilding this one) or just take my chances.