I am chasing down a vacuum leak.
I replaced a worn late throttle body with a NOS early throttle body.

A throttle body rebuild post I came across shows a brass ring seal and a seal that goes around the shaft on the end where it enters o the throttle body.

Neither of the TBs I have have the brass ring or the seal.

Are there supposed to be a ring & seal on each side of the TB? Are these available? Are they necessary? Are they the cause of my vacuum leak? I can't detect any play in the shaft.
Picture I found that shows the brass ring
Click to view attachment

Pic of a post I found that shows all the parts:
Click to view attachment

I believe the brass bushing is an aftermarket upgrade. The shaft runs bare on the aluminum housing which will wear out over time. There is a seal on the 1.8 that goes here, not sure if they all had it.

Ok, that make sense. There isn't any play between the shaft and the aluminum housing so that must not be the source of my vacuum leak.
Next I need to figure out how to remove the plenum.

Yes, that bushing is a repair on the throttle body. I believe that is an oilite (or similar) bushing used to correct any play / wobble in the shaft. I did this to my TB a year or two ago following r3dplanet's thread from a while back.

Removing the plenum is small PITA, but not too much more effort once you've got the TB removed. Primary issue is getting the boots off the intake runners. Then it simply unbolts from the case, IIRC.

Plenums do crack, and it is a worthwhile place to look for vacuum leaks once the other usual suspects have been rounded up and questioned.

Thanks!