There were 2 kits made back in the early 80's that I know of:

1. BAE (cost was $900!)
RaJay Turbo
Stock Exhaust Manifold with a U pipe/adapter.
5 psi boost
NO wastegate

2. Callaway Turbo Systems (was very pricey)
Custom manifold
IHI Turbo RHB52 (too small)
Intercooled
(I called Callaway to see if they still had the parts but they sold it all to some mercedes collector in the early 90's and don't remember who.)

I think ARKAY made a kit too. but never seen one.

If I were to do it again i would not buy a kit and just MIG weld a flange to the stock exhaust manifold. use a T-3 turbo from a Ford Thunderbird and Intercooler from a SAAB. 7 psi boost and it will be a blast! I think you can get all the parts for less than $700 with a rebuilt turbo. I have seen some of these turbos on ebay sell for $300 rebuilt so that would be cheaper!

My quartermile time dropped from 27 seconds! to an awesome 20 seconds! GO DIESEL! and my mileage went up to 28 mpg from 24
the car was an automatic and was still slow until it reached about 20 mph. The turbo sizing was incorrect.

good luck!

__________________
WARNING: Bastard Mercedes Builder/Tuner
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Thanks