Well I was getting the back doors on the Suburban to lock intermittently. like they were just not pushing hard enough to work the lock system.
Got on Advance Auto Parts website and they were the cheapest at 50 bucks each. Replaced the ones for the back doors....was not hard at all...It took longer to get the darn door panels off than to replace the actuators !! They work now witha nice, positive "clunk" when ya activate the door lock /unlock button.
Lotsa researching it here but I was convinced it was simply the actuators.
Don't make it harder than it needs to be, and I was right.

It's a 1999 w/ 100k miles. low miles so I figger it had done lotsa short trips thus using the door locks more than if it had been lotsa highway miles.
....and simply wore out the actuators.
but easy fix...just do it ...don't pay the "stealer" to do it !