I have a 69 F100 131" wheel base. The truck is all original and in very very good shape, great patina, etc. 2WD. I've had two different friends tell me on two different occasions that something doesn't look right when they are following me down the road. It almost looks as if the front driver wheel sticks out past the rear wheel when tracking down the road a couple of inches. Now, I don't mean the truck is tracking crooked...I've seen vehicles like that that seems like the whole rear of the vehicle is off to the side. The best way I can describe it is image if someone put a wheel spacer on the front driver side but no other wheels. I don't mean the front wheel is laying out at the bottom...it's like the whole wheel is out. The passenger side lines up fine with the rear. All the wheels are the same (same backspacing and all that), and it does not appear to have a different spindle on the driver side.
The truck travels down the road very straight, doesn't road walk (no see-sawing of the wheel to keep it straight), etc. I guess I'm not too worried about it, but it does bug me a bit.
I know it's hard to diagnose, especially since I can't get a pic (looks like it sits straight in the driveway
) Maybe both of my buddies are just nuts. 
In '73 they widened up the rear so front and rear would be the same,