Truck: 1994 microcab/shortbed, 130k mi., 5spd, 2wd, 4g64, AC, PS

Symptoms:
The steering wheel doesn't return/straighten out after making a turn (it will maintain the same radius with hands off). The power steering also seems less effective at higher RPMs.

Belts are tight and healthy. The fluid in the reservoir is red without bubbles and doesn't seem burnt/brown. Ball joints and steering components aren't perfect but I've only noticed a couple worn boots. None are seized or excessively loose.

The pump is cheaper than the steering gearbox, so it's the obvious place to start, but I was wondering if any other MM/D50 guys have R&D'd similar symptoms BEFORE I throw money at it.