I have a friend with a 4043 just like mine. He wants to convert to a Dual action. I can do the work, my question is will the 2nd generation hammer assembly and sears work in the 3rd generation pistols. I can find the parts cheeper on auction sites thats why I ask. The only part that concerns me is no decocker or safety may bey a new saftey assembly too. Would be hard to decock otherwise.
If you are talking pre-TSW 4043 I would think the longer slide and frame would come in contact with a standard hammer. By the time you got the parts, safety body, decock levers and everything else, even if it did work you would probably have more in it than you would trading into a 4006.
If that's an early 4043 there is also no room in the frame for the decock lever. There's only room for the one lever, the firing pin safety lever, to the right of the hammer.