Drove 100 miles total (to town for periodic lab work, then 50 miles to the nearest Lowe's for home repair supplies, then 40 miles home). Truck ran fine and did not leave puddles anywhere. Steering box is still sloppy
But the new rear brakes had developed a "shudder" which kept getting worse on each application at 45+ mph.
This afternoon I pulled the drums and could see pronounced chatter marks on the shoes, significantly worse on the right. Looks like I didn't break them in properly. So I lightly sanded the shoes and drums, cleaned everything carefully and put it back together. I did a more careful break-in and so far so good, but didn't get a chance to do some 60 mph braking.
The good news is that there is no sign of oil contamination anywhere so the conventional axle seals I recently changed seem to be holding for now. I have a pair of Scotseals (which is what I should have bought the first time) and will use them if there is any leakage.
There may be an issue with the left rear parking brake cable binding, too... thinking of returning it to O'Reilly and buying a better (non-China) one.