No. I believe the center position is the where the bolt drops the lowest. You can eyeball it by looking at the stops on either side of the bolt eccentric washer.

It's not really dropping that easily by itself from turning the bolt. It will if I roll it back and forth and bounce on the bumper, but it's still a little new and snug.
The FSM shows a pic implying the center position is to the side, but I guess I will see what I can feel out.

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1982 300CD Petrol/Black Leather

Okay, new tie rods are in and adjusting their full travel, so the toe is now fine, but I'm still finding it difficult to adjust the camber. I have positive 30 minutes on the passenger side, with negative one degree on the driver's side, and I can't seem to change it. I'll do some driving tomorrow and see if it settles in.
Another interesting element is the caster reading. On the driver's side, I get close to the same value turned in as turned out, around 4 degrees. On the passenger side, I get 5 and a half degrees turned one way, and 2 and a half the other. Yes, both sides work out to 8, but am I adjusted too far to one side of the car, or is this to be expected?

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1982 300CD Petrol/Black Leather

Toe-in is most critical to the tire wear and how the car drives. Ideally, you want the front tires exactly parallel when driving. Because of play, the tires toe outward from the driving force. You want to set slight toe-in to counter that. BTW, FWD cars set slight toe-out since those tires pull and toe inward when driving. The M-B manual wants you to push the tires in toe-out direction w/ spreader bar, to simulate the driving condition and take out most play. The remaining toe-in they spec probably intends to account for later wear of steering joints and sag in the springs. U.S. cars with similar steering setup don't spec a spreader bar, so probably not essential, just allow another 1/16" for play, assuming your parts are tight.

I measure toe-in w/ a tape measure, subtracting AFT - FWD distances across the 2 tires. My tires have straight channels which make this easier. You also want to adjust so the steering wheel is straight while driving, which often takes a little trial and error. You will see that even 1/8 turn of the adjuster is easily noticed on the tape measure, so I wonder how a laser machine can do better. Indeed, former techs say they would sometimes bump the wheels and jigger the machine until all showed in spec, then print the report, i.e. cheat a bit, so might not be any better. A good final check is to hold the level against the front wheel and sight at the rear wheel. It should fall ~1" off the rear wheel on both sides (FWD is easier since view line falls on the rear wheel). If not equal, drive forward to center the wheels first. Drive the car around the block and measure again since may shift slightly. If steering wheel is cocked when driving straight on a road w/ slight camber, turn adjusters the same amount in opposite adjustments and try again. Think hard which was to turn them. You can actually see the wheel move as you turn slightly.

For camber, I hold a 4' carpenters level vertical, resting against the fender at the top and slide the bottom until perfectly vertical, then measure from level to rim at top & bottom. You want the top leaning in slightly (~1/16"), meaning "negative camber" to give better cornering, w/o excessive tire wear. Indy cars are set w/ extreme neg camber. It is more of a personal choice than exact spec. Set 0 camber for the least tire wear. Some older cars set slight positive camber (tires leaning out).

I never worry about caster, but would if I replaced the guide rod mount. In many cars, it is not even adjustable. Caster is where the line between centers of upper and lower ball joints projects onto the road. It should fall slightly in front of the center of the tire contact patch. Caster is the "shopping cart" effect where the wheels will try to follow the direction of car motion. In my 1960's Mopars, one strives for the most caster possible since the steering was designed for bias-ply tires which don't deflect as much as today's radials. We use offset bushings to get there.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

The FSM calls for 0˚ 25' +/-10' toe with wheels pushed apart with 110-120 N.
I have a giant clamp that works as a spreader, inexact but functional.
Measuring at the rim (15" diameter), I figure one degree of arc to be around 3.2mm.
So... the difference between the back and front should measure a scratch less than half that, or 1.5mm when the wheels are being pried apart with around 20-25ish pounds of force.
But I think that left me with positive toe the last time I set it up that way. I'll try it again since I've changed all the parts.
I wouldn't worry about caster either if this were just a regular alignment. I replaced the bushing where the guide rod attaches to the LCA, and they took too much caster out the last couple times I got alignments. (I measured it at 4 degrees and it doesn't seek center like it should.)

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1982 300CD Petrol/Black Leather

With a little help, I re-measured the distance between my "fishing lasers" and found the rear off by an inch. So, I added 12.7mm to each side, making the stand-off 100mm from the rim of the hub in front, and 134.3mm from the rim of the hub in the rear.

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1982 300CD Petrol/Black Leather

I bought a hunter alignment machine and rack a year or so ago to play with and learn how to do my own alignments. I need to get it hooked up and going.

I don't know all of what that system includes. The "Tenhulzen" setup looks like it should make things easier.
I sure would like to read the caster with the wheels at center position, though.
I just have a wooden apparatus with a pendulum, and some pizza pans with grease between them.
Theoretically, it's pretty simple.
Guide rods - caster
Eccentric bolt - camber
Tie rod - toe
I also found a spreader bar online for about $100. It's a spring-loaded deal, something like a professional-grade shower curtain rod.
This is actually getting closer to how the car felt when I bought it. It's finding center again, so that's good.

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1982 300CD Petrol/Black Leather