So I'm just getting around to changing out the PHH on my 80 series and while gathering my thoughts, I came to wonder what is so special about the PHH? After all, the engine compartment and undercarriage is full of rubber heater hoses. Just of the top of my head, there's the two for the rear heat, two next to the firewall, the PHH, and a few others. Should I not be changing all of these out? Am I missing something? Is it that the PHH is better fixed in the driveway than on the trail, while the others are easily accessible? If I'm doing one should I not do them all? Any estimates on total length of hose to purchase? Thanks.