kdub

Hello everyone I have a 64 f85 with the v6 . As stated I need help with this fitting. So there is a T just above the water pump and a hose goes from there into the coolant heater. From the coolant heater the hose goes into this cubed fitting which then goes to the reducer which then goes to 90 degree angle fitting which screws into the bottom of the engine. Does this sound right? If so, where would I find another one of these fittings and what is the purpose of its shape? Just seems odd to me and it gets reduced quite a bit which also seems weird to me. Thanks!