Whats the difference ? 4150 question !

What’s the venturi size on that BLP body...... and what size throttle bore is it used on?

From what I can find it looks like 1.590 and 1.610 venturi are the options with 1.750 throttle bores.

IDK but unless you are using that big venturi on something making over 700 HP it needs an annular booster and that’s coming from a guy who is having to rethink his stand against annular boosters.