It's Ok, it's not that serious,,,, The wheel brgs are 2 ball bearings pressed into a "hub" (when they fail there is actually not much "play" in them) it's all about noise at first. But NO, it doesn't mean you have to replace those.
Read the link on guzzles page. It's about maintenance but has everything you need to replace them. They're cheap and, depending on your mechanical background, a pretty simple job to do (it looks more complicated than it actually is)
So, here's how it all works,,,, when you're in 4WD the stub axle (it goes from the U-Joint through the center of the hub) spins at the same speed as the wheel. No need for the needle brgs to do anything.
In 2WD the axle, U-Joint, & stub axle all are stationary while the wheel is turning so, the stub axle needs some support inside the spinning hub. THAT's where the needles come in AND if they're shot you hear that noise.
A search here on the word "needle" would bring-up lots of threads I'm sure
With my 14v Dewalt impact wrench, a 13/16s deep socket, and the right snap ring pliers, I could change a side in under an hour (NOT the first time I tried it!). Finding the Snap Ring pliers took the longest time to find the first time I did it
I would order the brgs from Ford (take guzzles part # with you) and, since you don't have vacuum hubs, I wouldn't even worry about the O-ring... The last time I bought the brgs they were around $10.