four wheel drive ?s

[1968k10blue]

I have a rockwell t221 and was wondering what it would take for me to be able to tell the difference between gears better, it just has a fairly sloppy warn out shifter. the other question is, when I engage the locking hubs and drive down the highway, it will vibrate like crazy. I think it has to do with on the driveshafton the upper U-joint there is a block with a second U-joint that only allows movement in one direction, not both, is this normal equipment? I would get a picture but it would be very hard to get a decent picture with the tranny crossmember in the way. thanks for the help in advance guys