Slip joint play

[Uncle Meat]

I was checking the driveshafts in my new (to me) 96 and noticed a very small amount of equal play in each shaft's slip joint.
How much is normal?
I'm trying to trace a small amount of vibration around 40mph when I'm accelerating.
U-joints seem tight.

Thanks in advance.

 

[landtank]

I replaced my rear shaft for slip yoke play. The new shaft had none that I could detect.

 

[KliersLC]

I have a bit in mine, but the PO neglected to EVER grease the yokes....

How many miles do you have and is there a driveline clunk because of it??