My recollection is that I worked from the bottom of the engine compartment, and alignment & re-installation were not a serious problem at all. I thought my pump exhaust line went into the intake rather than the crank case though!?!

The hose should run from the top of the vacuum pump to a banjo bolt on the bottom of the intake manifold which is located in the passenger side of the engine where the air cleaner connects to it not to the crankcase...perhaps you are not correctly identifying the intake? If that line is full of oil you have found your problem. You can disconnect the line from the IM and it will at least stop sucking oil out of the crankcase and burning it if you have to run the car at all that is a safe way to do it, at least in an emergency.

I would NOT run the engine until that vacuum pump is fixed. The repair isn't hard; you can do a search for psfred (I think) who is Peter from Indiana - he did a nice write-up, and I think he hangs out thesedays at the vintage forum. Or you can call or e-mail Phil at Fastlane (one of the tabs at the top of the website) and purchase the service CD. The service CD has been well worth the money for me, and buying parts from Phil keeps this "free" website going.

One thing that I've found very helpful when working on a bit of machinery close to the radiator is to use a piece of fiberboard, 1/4" ply, old vinyl flooring, literally anything, to cover exposed radiator fins and prevent a slip of the wrench from turning into a damaged radiator.
Just last month a mechanic ignored my suggestion that he do this while working on my truck, and then banged a hole in a big (four gallons just in the radiator) radiator for a 3208 Cat. It didn't cost me any money, but the time involved in draining the system, unbolting the radiator, soldering, rigging a pressure-test, (resoldering), then putting the whole mess back together gave me plenty of time to reflect on the value of protecting radiator cores. With a Mercedes with a fan shroud this won't be much of an issue until and unless you decide to remove the fan to get better access to the vacuum pump, which will make the radiator core easy to poke.
Even two layers of cardboard are better than nothing.
SEO

If the discharge from the vacuum pump on this engine is going to the crankbase, I don't see how a faulty pump would cause smoky exhaust. It would just be pumping oil from the top of the engine to the base, and wouldn't be pressurizing the base enough to cause blow-by, unless that vacuum pump moves a lot more air than I guess it does.
On the other hand, the loss of brake boost points to loss of vacuum...
Which leads to the question: what about the rest of the vacuum system? Do the door locks, or the engine shut-off, or any of those other clever and oh-so-convenient Mercedes vacu-servo luxury devices still work? This assumes they were working before the recent smoking/shuddering events...
Anyway, my first guess upon reading the initial post was that this was a case of bacterial slime or rust particles or some other crap causing the delivery (pop) valve in one injector to stick open. This would cause shuddering (running on three cylinders while the fourth cylinder injects early and late at low pressure, which would contribute to the shuddering and loss of power, and be the source of greyish-white smoke.
This would not explain the brake problem.
With any diesel that's been out of service for a while I'd suggest that you change fuel filters (duh), and cut open the old filter. If it has black thread-like tendrils on the surface of the filter medium, that's bacterial slime. There may also be a smell like sulfur. If you find that, you need to go to a fairly aggressive program of getting rid of the slime. Slime in the tank and transfer pipes can be removed by using a fungicide in the fuel, changing filters a lot, and burning a lot of fuel. (I have worked for tugboat companies that buy "Bio-Bore" fungicide in 55 gallon drums. Because it works. Certainly not because it's cheap, because it isn't.) End of product endorsement. I've also known tugboat company port engineers who mix diesel calibration oil with Twenty Mule Team Borax, agitate thoroughly, then filter. It's essentially the same as Bio-Bore, which used to be made by US Borax Company. This might make sense for a company that has 10 boats running, each one burning 2,000 gallons of fuel per day.
In any event, all of this procedure will not get rid of contamination DOWNSTREAM of the filters. The important thing to remember is that the microscopic spores of the bacteria that live in diesel fuel can pass through a very fine filter media, into the injection pump, high pressure pipes, and injectors, and if the engine isn't in operation, they can multiply their numbers in biblical fashion. I remember once opening the side plate of the injection pump on a Caterpillar engine that had been out of service in a boat that was laid up for several years in a Louisiana bayou. The fuel gallery was full of gritty black granular material that looked and felt like very fine sand-blast grit. This was the remnants of the calcareous exoskeletons (those are real words, honest) of the bacterial bugs. This material is very abrasive and will score the highly machined surfaces of the injection plungers and pop valves. The byproducts of respiration (a polite euphemism) of the bugs is sulphur, which will combine with water to form the compound H2SO4, otherwise known as sulphuric acid, which will etch the highly machined parts mentioned above.
Simply using fungicide and servicing filters will not do anything to remove grit downstream of the filters. From that point of view the logical thing to do when returning diesel machinery to service after a long lay-up is to have the pump and injectors serviced and rebuilt if necessary, and flush or renew (replace with new) the delivery, high-pressure, and return lines.
Aside from using a fungicide, the best way to keep bacteria from colonizing your fuel tank is to strip the water bottoms off the tank, because the bacteria is active at the fuel-water interface. Some boat and machinery tanks can be stripped with a suction tube down through an inspection plate on the top of the tank. Many diesel cars have a drain plug on the bottom of the tank, and by loosening that until it weeps you can strip off water lying on the bottom. This is best done with the tank nearly empty.
Water gets into the fuel from contaminated fuel sources, and from condensation from the atmosphere. The more rapidly a fuel supplier's tank is turned over, the less likely that it is full of water and slime.
To prevent condensation, the fuel tank should be kept full, particularly during lay-up. The smaller the volume of air in the tank, the less condensation there will be as the tank sucks in (cold nights), and blows out (hot days)
Dunno if this is relevant to the problems described with this car, but I thought it might be interesting to some.

Never heard of one going to the crankcase...here's a snapshot of a '72 and I suspect the '70 is the same...the line is circled in green...perhaps the author of the original post can post a shot of his if his is different than this.

Some vac pumps (the later ones?) have a single line running from them (the vacuum line) and just discharge into the crank case.

I don't think any of the early 70's ones did.

The vacuum pump exhaust on a 220D goes to the intake manifold. As far as I'm aware, the power options were windows, sunroof, and suspension. Haven't seen a 220D with an auto-transmission so I don't know how they work, but they're out there. Prior to the 220D the auto-transmission was about the same as 1950s American powershifters with solenoids for the wet clutch and gears. Manual transmissions are a dry clutch and synchro gears.

For seo, this is off-topic but the tank drain on these old Benz's have an o-ring. The good part of the story is that it's easy to put a tube down the fill neck and siphon from the outward facing "dent" where the drain plug is. The bad part of the story is that all the gunk likes to settle in that "dent" which makes it very hard to just loosen the drain plug and weep the junk out and then get that o-ring to reseal. I'd just siphon the tank then pull the plug, then clean the "dent" and replace the o-ring with a new one. And biocide the snot out of the next load of fuel, of course. Borax is a marine secret that is never, ever told to a roadie, especially a Benz owner. And up here we like Ford ATF when putting an injection pump to sleep.

Seo's story, interesting....
For dabenz----how do you administer the ford ATF into the pump?
How about the return to service?
TIA, marty

Umm.... ....this is The220D's thread about his vacuum pump. I assume he's searching, reading and learning. Can't wait to read about his success.

For Marty600, this is off-topic again but daBenz is basically a gravity fed injection pump. Pull the top off the cannister secondary filter, suck out the fuel with the handy glass turkey baster then fill with the ATF. Start the car and watch the injection pump return line. Or if you're really picky then these injection pumps have a vent plug on top and you can use that and a big syringe instead of the secondary filter. Put the tank return line into a can if you don't want red in your tank. A search of this web site will show you many (and sometimes heated) arguments about ATF in the fuel system. You decide what to do with your car....

Yes, I absolutely misidentified where the line from the vacuum pump goes. Mine is exactly like your picture shows. My apologies (yeah, I'm a newbie - I'm trying to learn and wrench at the same time).

The repair parts came today, so I plan on trying to fix the vacuum pump either later this afternoon or tomorrow. Too late to get the CD - darnit. I need to get this thing up and running, as its my daily driver.

Oh- And I can't post a picture at this point. I've left the car in my office garage, rather than having it towed to my house and put on the street. My thinking is/was that this way I can still work on her if it rains.

I'll try working from the bottom too. I can get a better look at the pump that way. Is this a 1 person job, or do I need to enlist a buddy to help hold anything? None of my friends mess with their own cars, so this will be a case of the vision impaired leading the blind, if I need a second set of hands.

My 220D has a manual tranny, hand crank windows, and no sunroof. I like her anyway. Despite the aggravation of the car 'breaking down' when I need her for commuting, I'm really enjoying learning about the beast and how to work on it. Perhaps these are lessons I should have learned earlier in life (I'm 34).

That's the best kind. :D