[Christ]

If it weren't such a hassle to put the merc on the road, I'd say to do it. That way, you can get the motor set up to run on veggie beforehand, and you'll know any "quirks" that it has, and be able to fix, identify, duct tape, etc.

To be honest, you're treading dangerously by taking someone reliable off the road to put something unreliable into it with absolutely no mention of whether it's going to run or not (or like running) on the particular fuel you've chosen to use in it.

Given time (which you apparently have, you keep putting it off while doubting that you should do it altogether, it seems) It would probably be better off to "try out" the car for awhile (few hundred miles, at least) to work the kinks out of the engine and transmission, at least.

I'm not tooting about your mechanical ability, because I have absolutely NO idea whether or not you can do the swap on your own, or even with help from friends... I do tend to wonder if you've measured the diesel and the bay it's going into yet, though. (Yeah, 350's fit.. they're tight, and they're the same length as the 2.2 liter plus a small bit.)

The plus side toward using the tranny from the merc too is that you'll have to make a custom tranny mount which will let you mount it back further if you need to, so that you can clear the engine in the engine bay.

So I guess if you're looking for something to do, and you're not going to bother putting the car on the road to work it out a little bit, maybe some preliminary measuring and cleaning up is in order?

How about degreasing and removing the unneeded bits under the hood? How about familiarizing yourself with the electrical system and components of the truck you're using? Have you glanced toward a wiring diagram? Have you checked the type of electrical connectors you have, and how to release them?

What about looking into the gear ratios for the S-10 that are easily available, and checking on what ratio is in the rear of the Mercedes already? Maybe they're actually pretty close ratios, and a gear swap isn't going to be necessary right away.

Maybe you could think about how you're going to make the speedo work? Tach? Which gauges you're going to use? Tire size? Radiator?

There are literally a hundred things you could be doing at this very moment... instead, you're reading this post, thinking about what to do next... :P

Get 'er done!