those made after about 1965 have a 2-piece lifter. The older one-piece lifter guns are difficult to retrofit. It is not a home gunsmithing job for the average shooter.
The cutover from one piece to two piece (aka 'Fast Load' system) occured in the mid fifties; I have a 1954 that does not have it and two 1955/1956 guns that do. There is more to the conversion that just swapping out the visible lifter, and while it's not rocket surgery it's also not something that you can do without knowing how the system works. Last I looked, replacement bits to do the swap ran well over $120.