I've got lots of questions and just know you guys will have the answers!!!

I have gone through search but am not finding all the details I need but lots of good information.

I've just purchased my first MBZ, an '83 300SD and am awaiting delivery of it.
I also have a soon to be 16 year old daughter that needs a car and doesn't think an MBZ would be too tough to drive.

Now, in my own podunk town, I have spotted a '79 300CD for sale and have a lead on a '78 300D parts car reasonably near. By parts car I mean body and interior only, no engine or trans.

Here's the questions that dad (the mechanic) has asked me to post to know whether we should get "in for a penny, in for a pound"!

Is the AT for the '78 D and the '79 CD the same? (W4B025)

Are the differentials & ratios the same and/or interchangeable?

How about misc. parts? (Door and window mechanisms, wiper motors, AC units, power steering units, vacuum pumps etc.)

The '79CD shows 398K on the odometer and what appears to be fair to good maintenance. Can you give any suggestions about things to be aware of and special other than the normal things for a car of this mileage?
I know that there are certain things that are specific to the CD but is there enough in common with the D to make the parts car worth my while to get??

The CD has been sitting awhile, lots of pine needles left in the channels, there is a pencil sized hole in the passengers side of the front cowling about 1" below the window channel. Is the cowling a bolt on piece (I sould get off the parts car) or a 1 piece unit along with the pillars and windshield? Is is going to be a real bugger to get at and fix? I have read the threads about the weep holes filling and rusting everything out in that area.

We haven't heard it run, just an external look-see. There is recent work done on the drive train as evidenced by NEW bolts, and also has new shocks on the rear but not the front. Interior is so-so, usual dash cracks and top of rear seat splitting, drivers seat has a 5x6" spot on the outside back bolster where the MB Tex is gone down to the fiber wrap but not a huge crater. The trim around the base of the rear window drivers side window has come up, isn't torn apart just coming loose away from the body. The trunk is dry, doesn't have that musty wet smell and the window and door rubber has seen a lot of exposure to the elements.
I know that the rubber parts can get to be an expensive fix but all things in good time if overall this seems to be a good investment. They are asking $1800 obo.

Dad is a professional mechanic, over 35 yrs in the trade, with experience on autos, diesels, heavy equipment but limited exposure to Mercedes specifically. But, I have learned over the years, if he says it is something he is willing to work on, that is like a blessing from the Pope. He likes the older stuff, we currently run mid 80's and older Ford 300 6cyl's.

What kind of comments do you have for us, should we run, run fast in the other direction, or look closer??

In my opinion, I would pass. Look for a 1981+ and you can have the MUCH better power output from the turbocharged engines.