'78 K10 radiator overflow plumbing

[projo198]

PO did not have an overflow tank and the hose attached to the radiator just below the fill shoots coolant out when hot.

I looked up the appropriate tank for my truck but it appears to have 2 inlet/outlets.

Does my truck recover coolant via vacuum through a single hose, or am I looking to tap a return hose to somewhere on the radiator/motor?

Thanks in advance!

 

[PrairieDrifter]

78? Should be a single in line through the top off the overflow tube and a cap. The hose needs to be long enough to touch the bottom of the tank. It does siphon in and out, with temp.