Just get her drivable (7 Viewers)

[WarDamnEagle]

The gasket goes on the flange and the collar goes on the stub end of the exhaust pipe. There should be enough exhaust pipe sticking through the flange to accommodate both. Not sure what you mean by the collar being unsymmetrical. It should be perfectly round but with a U shape cross section which goes over the exhaust pipe stub end (with the U inverted).

FWIW, Toyota still sells that gasket for half the price of CCOT. https://toyotaparts.ourismantoyotaofrichmond.com/search?search_str=90917-06003

As far as I can tell, that collar is NLA.

 

[onemanarmy]

that is perfect.
thank you!
its not symmetric in that it has a "u" shape cross section as you show so it was intended to be installed a certain way and not just as a spacer.
(and I got the gasket from Toyota, just used that link as an example....thanks again)