I picked up a Blue W123 1983 300D turbo diesel for $300.

This was the 'fully loaded' last--year-model for the W123 chassis, sun roof, power everything. The only interior upholstery wear is on the driver's seat. Original floor mats. Original --everything--. About 300K on the clock, the odo cable blew out and I've yet to replace it.

The previous owners (AKA "IDIOTS") had parked it for well over a decade, covered in road salt, and the body is now un-repairable.

The drive-train, however, was nearly perfect. The brakes and the radiator were the biggies. Four wheels, three different models of brake caliper, and two totally destroyed disks. All four new, and same model now. Going is good. Stopping is better.

Scoured out the fuel tank, put in a new vacuum pump and secondary fuel pump, some brake lines and other hoses. New battery, flushed the crankcase, clean oil, clean fuel, and some fiddling to get the glow-plugs to work again. (Key switch is shot. There's a button on the lower-left of the knee-kick, driver's side, that fires the glow-plug relay now...)

Once it was all back in one big pile, it started after about twenty seconds of cranking, on a brisk 7C day (that's about 45F for the metric-impaired). Big puff of white smoke. Rattle-rattle-rattle for ten seconds, then the oil pressure was up and it has been running like a top ever since.

I had my buddy who owns a shop take it in and do the repairs as bits and pieces when his shop was otherwise idle. Took about a year to get it road-worthy again, but it was worth it. It will never LOOK good, but I drive it nearly daily, and use it as a great big tool-box.

I do odd job work for some local restaurants, now that I'm officially retired. Since they throw it away (recycler gets it for free), I have been known to scavenge 20 or 30 litres of used deep-fryer oil to mix into the rock-diesel from the petrol station. (Only during hot weather!!) It smells like tacos, or sometimes fish, going down the road, but I get upwards of 15 km per litre (that's about 35 miles per gallon, give or take).

I really love this old behemoth. Drives like a dream. I'd love to find a chassis and body with a blown engine, and swap the good parts from this one into it.

Anybody know where one might be found??

You'd need to try eBay or Mercedes/classic car community specialist websites, and expect to travel far to find the perfect car. I like these old Mercedes also.