I rebuilt the turbo for my 1982 300D turbo last summer. Sounds like you need the same parts that I needed. The parts cost $16.39;shiping and handling $5.92. Total of $22.31. The place for parts: M&M Distributers; Houston,Tx.77261.Phone No. 1-800-392-5517. Mine was a Garrett turbo. MB used two makes of turbos, so have all the information handy when you call them.
Be sure you mark the parts when you take it apart. The alignment of the oil return line is important. Other than the oil return line alignment, the job is fairly simple. No special tools or equiptment needed.
If you want, I can send you a list of the parts I needed to rebuild my turbo. Nothing to it. Who says you can't rebuild the turbos? Lots cheaper than getting one from a parts house. I was quoted prices ranging from $495-to over $1,000.
Bill Lewallen; Lexington,Ky. Where diesels purr and turbos whine