I had one of the main cooling hoses split on my 99 S80 about 600 miles ago.

It was replaced, but the tech at the time saisd it would be wise to replace all hoses considering the age of the car.

The car is early 1999 and has done 45k miles

Any advice on this.

 

Might not be a bad idea to replace the rest.
You should be able to replace them one at a time it you really need to.

 

How many coolant hoses are there anyway. Im thinking of replacing the coolant hoses on my 99 S80 with 147K miles.