I'm familiar with these since I rebuilt my 3-on-the-tree manual when I first got the truck.
You can see the old spacer here when I took mine apart...
And you can see the new one installed here between the two shifter arms. I believe there are two spacers in there if I recall correctly.
1984 F150 4X2 Flareside. Mild 302 w/GT40 heads, BBK headers, Holley 4bbl, Comp Cam, M5R2 5spd swap, Magnaflow full duals. Blotchy paint, original bare bones stripper.
2013 Volkswagen Golf TDI My new fuel sippin' mile-eater for work.
2015 Lexus IS250 AWD F-Sport Mrs. Rembrant's ride. Far too fancy for me. All I do is wash it for her.