I have just become very aware that this is a critical component to
periodically replace (after failing HC high rpm emission).  Seems fairly
straight forward to do if I could only see where on the exhaust it is
screwed in.  I would have thought before the catalytic converter, but
I can't see anything between the catalytic converter (I assume is the
cylindrical 'bottle' just after engine manifold) and the manifold. Any
suggestion much appreciated

thanks, guenter