I just went to my local German car parts (try German,Swedish & French car
parts,  mail order tel 02089173833)  and managed to get everything except
the heat shield and the cast 2 into 1 knuckle (at the left front of the
engine). These were from the main dealer only..   My crew cab didn't have a
cat though.

The 2 in 1 didn't need replacing in the end,  as it is thick cast metal
you'd have to smash it quite aggressively to break it,   just get a grinder
and cut the bolts off (a cheap grinder costs less  than the part itself).

Be careful if you're DIYing it,   things can and probably will get messy.
I ended up pulling the engine out and having to replace all the manifold
studs due to shearing off.   In the end I replaced them with 10mm (instead
of 8mm) stainless steel.  In fact all nuts and bolts with stainless steel.

Good luck
Dave Sov
Dublin  Ireland

Not trying to put you off!