Welcome back sky. Haven't seen you on in a couple days.
Sealed systems are a good way to go, I like them. I'd replace it too. I have the same issue on my 84. You know the other day in the 85 K1500 when I was driving it for the first time I kept a good eye on the fluids. I was sure happy to see when I kit the pressure lever on the cap, it started filling up the recovery tank.

Even the recovery system is working good. So without the recovery tank working, its normal for your truck to look to be about an inch and half to 2 inches low on coolant when cold. That gives that 1 1/2 -2 inches of space for expansion room before it starts spilling out your overflow sicne its not going into a recovery system. Oh, and stay off the racetrack if you don't have a recovery system.
