What's your tolerance...
Every fleet owner is excited about reduced maintenance. A responsible service manager understands that this does not mean you can turn a blind eye to the maintenance-free components. As an example, maintenance-free drivelines eliminate the need for greasing. As such, the products provide no grease zerks, but that does not mean no inspections.
You should always adhere to the manufacturer recommendations with regard to inspecting the products for wear and operational incurred damage. Some products require inspection every 25K miles and others every service, refer to the product manual for intervals. For drivelines it is important to check any play in the U-joints or slip shafts and document your findings. Full or half round yokes have the same tolerances. To check the yokes, move them up/down, and side to side with at least 50 lbs. of force. Basically speaking, there should be no free play. Most documents indicate .006” using a dial indicator, but my thought is if you feel anything, it’s time to replace the joint.
If it is necessary to disassemble the driveline and slide out the slip shaft, make sure you mark both pieces in an effort to avoid mistime within the assembly. As drivelines rotate and age, center bearings have a tendency to wear. You want the driveline aligned as it has previously worn when you put it back together.
Spicer has a nice calculator online to find operating angles for each u-joint. See link below. If you have another manufacturer, ask the product rep for direction.