12.7 waterpump o ring

i bought a waterpump “Gates” from FleetPride, and o ring was missing, I stopped at Freightliner and got one. However it wasn’t a round, but a thin square one. Looked at their waterpump for my Truck, same o ring. Verified the same at another Dealer. Old waterpump had a round o ring.I ended up getting a new round o ring. My question is has anyone installed a waterpump on a 12.7 using the new thin square style o ring.It acts like it wants to lay down into the groove, when installing waterpump. Like a leak waiting to happen.Another thing, I’m wondering is what’s the difference between Gates greenline and blueline hoses? I somehow got 1 of each. Never heard of Blueline before.