Lots have changed since the 1950's, maybe even the river water.  Our river was brown when it got up and out of the channel, full of sand and sediment, easy to get through the seals and into any bearings we had then.  We were surprised at the bearings also at the time, didn't seem they would fill up like they did.  Sand and sediment also got into the brake drums back then, caused a lot of failures.  One local crossed the river, got to the pool hall three miles away in Hidalgo, brakes failed from being waterlogged, and went through the windows and bumped a pool table.  We learned to "ride" the brakes for a while after crossing water, just to dry out the linings so we could stop if needed.

Don't take my remarks personel, but you seemed so sure you knew about what river water does (or doesn't do) to bearings, and my experience was very different.  Perhaps the rivers in Kansas don't flow as fast or carry as much sediment as ours in Illinois.

As always, things may be different in your part of the world, I was just sharing what my experience was with driving machinery through water.