Alas, I am afraid that I can't help out on this one.  I have no idea where you might find one.

 

Perhaps some of our other contributors might be able to help on this one.  Individual SUIT sight parts are generally seen about.  You might want to try either SARCO, Inc. or Numrich Gun Parts, but if they don't have them I don't know who might.

 

Sorry.

 

MG