that sounds like you need a u joint.

 

a little play is normal. (so long as it isn't the u-joints that are doing it.) The t-case saver is a good idea on any 231 t-case, as the snap ring really isn't as reliable as it should be.

 

the u-joints dont have any play in them but im sure theyve never been replaced and i have 110k miles on my truck, but you can rotate the drive shaft about 3/4'' each way, i know its not much but lately ive had a slight jerk when i go from R to D,

 

that's normal.