Might be hard to find MB parts in Fairbanks, Ak., compared to here in Calif.
You don`t need the Trap Oxidizer living where you do. was a calif requirement, and was/is a factory replacement item done at the dealer. It is part of the smog warranty.
Some have added a coustom made pipe to relace the Trap.
I changed my 85 cali 300D several years ago, by changing to they had them in 83. picked up all the parts for the Trapendectimy.
If you can find a 78 or 79 300SD, those 2 yrs didn`t have the EGR, so nothing to close off in the manifolds, and looks much cleaner.
The 85 300SD & 300D use the 2:88 differential. a one year thing.
Here is a DIY from the Resources Tab at the top of the page.
PeachPartsWiki: Calf. to Fed. Emissions Conversion
At the rear of the intake manifold is a Banjo Bolt with a pressure line, remove the bolt and make sure it is clean, and not plugged with black goop from the EGR and blow by oil.
The pressure line goes to a switch over valve and then to the ALDA, the square thing on the Injection pump. make sure this line is also open.
I blow it out with Brake cleaner and blow it out with compressed air.
If this pressure line is plugged, it will cause your engine to become doggy and gutless.
Charlie