The RM exhaust system is fairly straightforward and the commonest sections to fail are the flexible pipes.
Here is a diagram of the standard AEC exhaust from an old Truckmaster catalogue.
The original AEC part number is shown with
the Truckmaster and Wasey equivalents. None of these three suppliers is still
in business but a good commercial vehicle exhaust supplier should be able to
cross reference from the old Truckmaster part number given above.
The Dinex part number for the silencer is 16304. The silencer is fairy easy to fit. Make sure you install it with the arrow on the casing facing towards the tail pipe!
Update (May 2008)
Iíve just bought some new exhaust sections. Dinex still seem to have good stock levels of them
The tailpipe (TAE22M) above is Dinex part number 16606 (£60) and the section next to it (TAE31B) is 16608 (£47.50).