I posted several questions on pre 88 rear calipers a while back nobody seemed to have any answers. I think I have some now.Kit doesn't include the actuators, I love this stuff when the kits called an Actuator Upgrade. New pistons,black oxide coated,note! without two way check valve in outer face!!!!This is the plastic/rubber plug underneath the disc pad in outer face of piston,what is does I haven't a clue. You'll find the plug listed in GM manual as #19 Fig 8 in 1988 manual pg 5B6-5.The stock Balance spring diameter is .095 New springs in kit wire size is .110 dia This info told me these calipers were never upgraded with recall kit. Everything else seemed identical to the original hardware.The only problem I had was finding a large enough spring to put on the E brake cable to make sure the monster counterweight does its job along w/ the spring.Any body that can add or counter this info I welcome your input. Thanks

The actuator is the piston.

Apeiron I've seen your posts and respect your knowledge,but on the pg.5B6-1 Actuator#16 is the 9 start screw that screws into the PISTON #18. I don't intend to agravate you over something simple,but I used the factory manual trying to determine what was supposed to be inc.in the upgrade kit. In the text it mentions screwing the actuator into the piston for assembly. I work from these manuals trying to problem solve/repair all my cars with my son.I just thought to point this out since it took an additional week of emails to GM parts to resolve this question. I was hoping this would prevent someone else from wasting their time. Thanks for your help

In the recall text the screws are referred to as "actuator screws" while the pistons are referred to either as "pistons" or "actuator assemblies". Regardless, no additional parts are required besides what's in the kit.

So is it true that I can look at calipers and determine if they have the rebuild kit by seeing if the check valve is present in the piston?? If no check valve, then rebuild kit present???

Not necessarily. It seems some defective pistons didn't have the check valve either.

Is there anywhere I can get the instructions for the GM 18019028 kit? I bought it and it doesn't have instructions

Check the 10-Bolt FAQ.

JamesC