Thanks to all for your advice on my last post RE the 280 twin-cam 6 that had retarded timing.
In order to get this car really right, it needs the front exhaust manifold, which also is a cat converter, replaced due to a split in the stainless steel outer housing.
My local Mercedes garage says they are no longer available new from M-B, and since it is illegal to install a used cat on a car, he has suggested using a manifold setup from a 1978 or later engine and a new cat installed on the tailpipe under the car.
This would allow the use of the A.I.R. plumbing to keep it legal, as long as a smog referee approved it.

Has anyone tried this fix, and if so,what are the costs/pitfalls associated with it?
Thanks,
Nate

'79 300D
'86 F-250 6.9l Diesel