Just to let you know, the two pictures with the arrows are the
points that created the most play in the whole shifter "linkage" setup for me.
The detent plate has it's purpose, but even a new one probably won't cure the play in shift linkage.
I even bought a new lower shift arm, but I had to drop beads of weld
and file it down to meet raised boss on shift tube.
I should have done that on the upper end of shift tube,
welding on the edges of boss on the tube, so it fit perfect with shift collar.
I did not, but I think you can buy a new shift tube if you wanted.
Possibly, if you buy collar, tube, and lower arm, they
will all be to spec and not introduce play.
I think it is a lot cheaper and easier to drop small beads
of weld on lower shift arm and upper tube. Then file
down until they fit is perfect with old corresponding parts.