81' 300cd brand size fuel hose???
 

i'm in the middle of repairing fuel leaks associated with the fuel primer pump and inline fuel filter hose connections. all visible "rubber" fuel hoses feel and appear brittle and worn. i want to replace... what size/type hose is direct replacement... I've been told 5/16, online i see mm sizes, i see braided rubber and all rubber... correct me if i'm wrong... fuel line hose clamp are only used to hold the fuel line in place, clamps are not primary means to hold and secure the hose to the line. correct sized hoses should be snug to began with.??? what is the correct OE size fuel hose?? mm/sae? thx.

is the so called "cigar hose" appearance something that happening over time to normal hose?
i picked up the 5/16 sized fuel hose, metric conversion 7.90mm. wondering if 7.50mm is a better fit? although, 5/16 is good.