From Dehaas Single shots.
The 44 1/2 is made from a forging the 44 from a casting. If you can get a look at the interior and it looks like cast iron it is a a 44.
The 44 1/2 also has a milled recess for the block to ride in. The 44 block pivots on a hinge.
With the levers open you will see a toggle and link conecting the lever to the rotating block with the 44.
The 44 1/2 has the lever connected to the block pulling it down