Coolant pipes

So, I've not been on here for a few years...had to register again.
The old disco has been in the garden for a couple of years, its use it or lose it.
Got an exhaust coming. Service kit is here. New battery is on., starts on the button.
I gave the top coolant pipe a squeeze and heard a crunching sound. No doubt will have to change some pipes and flush. How many pipes should I swap is the question. Chur..

All of them if their condition is doubtful

I think what I'm asking is, you see a full lot of pipes advertised, they are not all for cooling system, which ones do I need to change.? They all look ok but? I dont want to be pulling every bit of rubber off that i can see.