What size of hose do I need and length, probably time to replace due to age.

 

Which hose do you need to replace? What year is your 928? If your talking about the majority of HVAC (& related) hoses) are all OD 3mm. Generally the hoses are plastic and age pretty well as long as they are not bent too much, chances are the leak is on a rubber elbow or the actuator itself.

 

1986 auto 32valve engine