Clarification LMS Carb Part

[dixiebonsai]

Please excuse stupid question.I need clarification.Working on meticulously putting back together a Briggs LMS Carb Model 125 Carb..Part Number 633 just sits in between carburetor body and throttle shaft?I did not find this part when I disassembled it.It sits on top of carburetor body and does not go down in it?

 

[bertsmobile1]

It is a seal to stop air being sucked down the shaft hole.
They are not fitted to all carbs and many are foam so fall apart in no time flat.
And yes they just sit between the top of the shaft & the carb body.

 

[dixiebonsai]

Thank you Sir