From VIN A30645 the front exhaust pipe section shows a short flange pipe at the front of the system on the left side immediately behind the catalytic converter. (see #10 in red below)

What purpose does it serve?

Picture attached, natch.

Need to know fairly soon if possible.

 

That flange bolts on to the cat, earlier cars had slip joints I beleive it is just showing both types, other than that it must be US specific as here in the UK we do not have that

 

Thanks.

It's very strange because it is only on the left side and not the right. (as seen on an actual physical unit, not the picture) And only from VIN A30645 and up, so maybe not until the later years of the series. Prior to that the two legs were even and had clamp joints as opposed to flanges.