I think there are 3 types of handles for tripping the 43 blade. The one on top like UT's and 2 that are on the right side. One has a T handle and the other more of a bent L shaped. I have 3 43 blades. 2 with the t handle and the other with the L shaped one. I'm guessing the a matter of when the blade was manufactured. I would guess the one on top would be the earliest design as I think that is how the 42 model trips.