What piece is this saw missing?

[bowzonly]

What do I need to hold this blade in place. I have both the pieces with the Allen nuts in them

[Clj]

If you go to the t bird website, there are a couple videos on there. One of them shows the assembly and how to change the blade.

[Bowguy67]

I’m not familiar w that particular saw but it may be two pieces.

[Deno]

The 2 pieces you have may lock onto the flat spot on the spindle w/ allen nuts to hold the blade in place on the top and bottom.
 
Pictures of the 2 pieces would help.

Deno