Yes, you do need it. It's in a bypass circuit that makes the water pump circulate coolant through the head until the thermostat opens. When it does, a disc in the bottom of the thermostat moves down and caps off the bypass, so all the coolant goes through the radiator. If the tube isn't there, the thermostat can't cap it off, and you never have full flow through the radiator.
Thanks Phil. I"ll let them know it's needed. When they drilled the water pump holes they went a tad big so the tube from my car head doesn't press in. I wonder if JB Weld would do the trick. I'm thinking it can't really go anywhere when everything is all bolted together. (or could it fall into the water pump?)
Oh I went with the boat head because it has hardened seats now they think it may need some new ones ! They couldn't see that out till after the drilling,tapping and new guides !!!