I just replaced my fuel pump with a rebuilt one (Thanks George Des) What better time to replace all the hoses? I searched on our site, for what size hoses would be needed. Found many posts but none had all the hose sizes needed. The factory used Metric size hoses. Hard to find on this side of the world!
In the hopes that this will help others, here is what worked for me on my 68 280SL:
Hose from the Tank to the inlet on the fuel pump: 7/16's
Hose from the Tank to the metal return line: 5/16's
Hose from the outlet of the fuel pump to the metal fuel line under the car just ahead of the rear end: 3/8's (Cut off crimped hose, and clamp on the new hose)
Hoses under the protective filler tube cover in the trunk to the tank vent lines: 3/16's (Possible cause of fuel smell in the trunk if bad)
All of these hoses are rated for fuel. The 3/8's hose (Pressure/outlet side of the fuel pump is rated for Fuel Injection 100 PSI Rating
I bought 3' of each size (Plenty left over) Only exception was the 3/16's need only 1 foot max.
All of these hose sizes resulted in a tight fit.
One other note, I used the special fuel line clamps that do not cut into the rubber hose when installed.
RB6667