Sorry, I typed thermostat when I meant to type transom.
The Alpha One through transom water tube came with two different sizes, neither of which were 1 1/4". There was a 5/8" and 3/4". The one used on the 454, which is what he has, is a 3/4". It then uses a piece of hose bonded inside the supply hose to adapt it to 1 1/4". The point was that the Alpha transom only has a 3/4" diameter tube and it would have to use some sort of adapter to get it to 1 1/4", such as the stock supply hose which would have to be modified to get to the Bravo pump.