These steel lifter arms push back the ratchet pawls so you can shift both ways.
34507-52
1952-1971
34507-52A
1972-1984
This part changed in 1972 when the factory changed from the plunger style pawls to the hook style.
The Iron Sportster trap door assembly holds the mainshaft, countershaft, and shifter mechanism. The Iron Sportster shifter comes as the 34009-52 assembly.
34507-52A
1952-1971
34507-52A
1972-1984 Here is the upper lifter installed and staked on with the two lifter dowel pins.