Went north to do some hunting...when we got to the "woods" I locked the front hubs manually (because my vacuum lines don't work 100% of the time (working on it...)
Spent a couple of days then headed home...at highway speeds of up to 70 mph...but I forgot to unlock the hubs (I was NOT in 4x4 mode).

Did I damage anything by doing this?

 

No, you just lowered your fuel economy a little bit due to the rotating axles and gears. Lots of people leave their manual hubs locked all the time so they don't have to get out and lock them. Personally I wouldn't do it because it does put a little extra wear on the moving parts. But one trip isn't going to hurt anything.

 

I used to leave the fronts on my '99 7.3, '03 6.0, and '04 6.0 locked in all winter long.

The '99 was all manual 4WD. Didn't even lose mileage, really, was just a little louder at highway speeds. No ill effects for the 4 years I owned it.

The '03 had originally been ESOF with the vacuum system, but those had been disconnected/plugged and Warn lockouts installed (t-case still controlled by the dial switch, so electronically). Other than lowering mileage by 1mpg and being a little louder at expressway speeds because of the extra rotating mass, I saw no ill effects over 5-6 years on that truck.

The '04 was again, all manual 4WD. I didn't drive it much in the winter and tried to avoid snowy days (it was bought for towing, I had the '03 as my daily), but I would still leave the hubs locked in all winter just in case. Again, no ill effects.

Long story short, no, you didn't break anything, and other than marginally increased wear you didn't hurt anything. In fact it can actually be good to lock in the hubs a couple times a year and drive around like that, as it forces the grease in all the u-joints to move around, and splashes the gear lube in the front diff around to keep things freed up. Just don't engage the t-case and try to make tight turns on pavement - THAT could break things.

 

On my 02 350, they stay locked all winter, I try to remember to unlock them when I drive down the mtn but that doesn't always happen, you're fine.

 

My 6.0 was manual 4WD. After a few years I couldn’t be bothered to switch them off. They ran that way until I swapped it, a good 60-70k miles later.

 

Thank you all for the reassurance!

 

I thinks it’s actually good to lock them in every now and then. Get that fluid circulating, and parts rotating. Keep those seals pliable.

 

Now get underneath her and grease those stub shaft u-joints (front wheel axle shafts). They have grease fittings. When was the last time they were greased?