I ran across an issue with my truck last week...
96 F350 CC LB SRW 4x4 7.3
Slowing to turn on to my road and began pulling to the right (toward passenger) each time I applied the brakes. When I parked I noticed smoke coming from the left (driver) side front wheel well. The next day after it had cooled, I pulled the left front tire to inspect. Had my son apply the brakes as I spun the wheel and it stopped, so there is at least a little braking power now since it's cooled. Looks like there's plenty of meat on the pads. No obvious leaks on the brake line. I did lock in the hub and the left side doesn't turn the front drive shaft (but the right side does). Not sure what the hub would do to cause this so that may be a coincidence.
My guess is that something heated up to the point where my brakes on the left front overheated and wouldn't work anymore, then the right brakes were the only thing working.
I figure I'll pull the hub lock cover and see what I can see there. Anything else I should look at?
Likely sticky/seized caliper slide pins. Remove the calipers from the brackets, pull the slide pins out carefully, clean the bores in the calipers, clean the pins, re-grease them with some high-temp grease, and re-assemble.
Also could be caliper pistons sticking in the calipers.
Update - I pulled calipers on both sides. The slides were all rusty and were obviously not replaced by the garage I had take care of my front brakes about a year earlier (while I was having the transmission rebuilt). That's what I get for letting someone else do it. I replaced the pads, new slides, greased properly, bled the brake lines on the front. Been working fine ever since.