The engine, should it not be changed already, would be a 300D most likely - which was the OM617. Parts for which are abundant in the markets.
The more essential and recurring suspension/interior titbits would be a whole different ball game.
I personally have dealt with 'Shamsi', located at plaza - one of the oldest in the business in KHI. That would be a good place to start.
Ask around there, i am sure you should get some leads.
Sorry can't help with the mechanic as am not based out of KHI.