Front to back heater pipe bore size (answered)

[Cruz]

Going to replace one of my heater pipes before it fails but I need to know the bore size for odering the correct GP80 hose and I can't measure the pipe without removing the pipe and losing the coolant butI need the van for getting the pipe.....chicken and egg situation

I am sure I have read somebody say they are 5/8" internal diameter.

[Cruz]

I have a bit of 251 265 057 here, just measured at just under 16mm, which would be right for 5/8's.