When or if I switch f150 into 4H, do all four wheels lock up and turn at the same speed?

 

Nope. The front and rear driveshafts turn at the same speed but you still have differentials. The front differential is open, so the wheel with the least traction will turn. Same with the rear unless you have limited slip or a e-locker.

What year and model is your truck?

 

it's 2017 4x4, only options are 4H, 4L, 2H...so your saying it's basically awd like my subaru when I.select 4H, or 4L.

I don't have option to lock rear axles...

 

No, it's not like AWD. There is no center differential, both driveshafts will turn at the same speed. At least one front wheel will turn, at least 1 rear wheel will turn. 4H or 4L is NOT to be used on surfaces with good traction.

What is the AXLE code on the door jamb sticker?