[87Skier]

When I was working on my truck a few years ago I had the hump cover removed. I drove it and could watch as my driveshaft began rotating when I got to highway speed. It didn't rotate anywhere as fast as it would have if it were engaged, but it definitely rotated.

I think the important question is if your shaft is turning at it's driven speed (either by a locked hub or from the 205 being partially engaged) or if it's just some component drag (spindles, axle shafts, or even gear oil circulation).

You could put a zip tie on the front drive shaft near the U-joint and hook it to something solid like the engine cross member. If your truck breaks the zip tie, it's definitely trying to drive the shaft and you've got a problem.