XUD exhaust manifold box

[FarmerPug]

Im trying to get the diesel engine sorted out before putting it into the 305, anything that would be tricky to access when its in the car is very easy to get at right now, so i took a good look around the parts i have to see what needs to be sorted out.
The first thing i saw was this unit on the bottom of the exhaust manifold:

its completely rotten, but i don't know weather its some form of early particulate filter or a silencer could it be blanked off as the exhaust gases don't seem to go through it.

[Doggy]

Haven't a clue.

Nowt on ServiceBox, is there?

[steve_earwig]

There is, for the 504 anyway - http://public.servicebox.peugeot.com/classic/ although it's not in a format we're familiar with Groupe 0, tubulures is as far as I got (it's all in French innit )

Particulate filter? Ho ho ho, you'll be lucky if that's even Euro 1

[steve_earwig]

Also Groupe 1 Echappement seems to be exhausts, however the only thing I can see like that is page 440 but that's on a petrol

[Doggy]

There are a few other examples, but all are for petrols.
It does look like the 'POT' is fitted instead of the front silencer. Wonder it it's some sort of resonance chamber and/or water trap?

Odd that it's got 'Printed in France', in English, at the bottom of every page, but everything else is in French.

[FarmerPug]

Could it be some way to reduce back pressure on the engine? I had a look on euro parts and they have this which looks similar to the part:
http://www.eurocarparts.com/ecp/c/Peuge ... 7f8&000879

It doesn't offer much in the way of an explanation to what it does.