So I've tried all kinds of ways to get my wagon's SLS system bled after restoring the system on my wagon. I have finally gotten the rear end to raise up now and sit at the correct level.

However, the driver's side rear is consistently 1/2" below the passenger rear side (measuring from the mercedes star on the wheel to the fender lip).
I'm not sure why this is, but I think it might be time for new springs.

When I bought the car, the SLS system was disconnected and rode only on the original springs with a pair of standard shocks retrofitted in. The springs had these metal slugs wedged in between the coils. There was also some improvised spacers made out of a single coil section, cut apparently from another spring, which sat on the lower spring perch directly below each spring. This was all done apparently to increase the ride height to make up for the removed SLS system.

Given the above conditions, can I assume that the reason for the unequal heights between the left and rights sides of the car's rear is because the springs are just worn out?

The other part of this is I've found a few parts sites that apparently list the wrong springs as a replacement for these. The correct Mercedes part # for a 1982 300TD is 123 324 06 04. However, on a few sites, including pelicanparts, the Lesjofors part number comes up as 42 568 02, which according to Lesjofor's catalogue is the part # for for the 300D.
Is the cross-referencing simply wrong?

The 300D rear spring generally costs less than the Lesjofor's recommended option for the 300TD - can I just use a 300D rear spring in a wagon?

Here's the spring info acc. to Lesjofors catalog:

# 42 568 02 (recommendation for 300D)
Wire Dia. - 16.00 mm
Free length - 360 mm

# 42 568 05 (standard duty recommendation for 300TD)
Mercedes
Wire Dia. - 15.50 mm
Free length - 357 mm

# 42 568 30 (heavy duty recommendation for 300TD)
Wire Dia. - 16.00 mm
Free length - 343 mm

Thanks for any insights.

Subframe bushings

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I replaced almost all the rubber in the rear suspension including trailing arm bushings, subframe bushings and the differential mount. I did hear that if the subframe bushings weren't seated all the way it can make a difference in level between sides, but mine both look like they're seated equally. Any other thoughts?

What brand bushing did you use?

Have you replaced the sway bar links?

How is the front ride height? Both sides the same? Sometimes front parts being bad will cause the rear to sit lower...

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I used a Meyle subframe bushing kit (123 350 01 75) which is actually for a 300D. But from everything I read, this can be safely substituted in as it is just a rubber composition difference, I believe, from the 300TD rear subframe bushing. The wagon-specific bushing kit can only be gotten from the dealer apparently and at dealer prices.
The swaybar links are new as well, and the front end has had all worn parts replaced including: new lower ball joints, good used upper ball joints, new upper and lower control arm bushings, new tie rod ends and new spring pads.

After replacing all these front parts, I got an alignment done at the dealer and the front is totally squared away.

The front looks a little high to me, but when I put a level on the trim, it shows up level, as well as can be tested in my carport (maybe it looks that way because the fenders lips are lower for the rear vs the front). The back end is not low in general, it is just the driver's side is 1/2" lower than the passenger rear side (13" for pass. rear side vs 12.5" for drivers rear side).
I have read elsewhere that the driver's side springs often get worn and sit lower because there's more weight there from the driver and/or because of the crown of the road.

It would be nice to know if there was some adjustment that just needs to be made to fix the stance in the back so I wouldn't have to go through installing another set of springs - especially considering it's only getting up into the teens during the day here.

if the springs are not broken, you could swap them...
or you could count the nibs on the spring spacer at the top, and get one with one more nib on the driver's side...

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I put in new 19 mm spacers at the same time I did the rear suspension work. I suppose I could measure my old spacers (one of them is being used as a jack pad for my floor jack) and see if that one is thinner, then put that on the passenger side. That might lower the passenger side by 1/2", though it would put the entire height for the rear at the low end of acceptable. My redneck mechanic side wants to just put that metal slug spacer between the coils on the low side.

I ended up buying new rear coil springs and 9.5 mm spacers (these springs were the longer-spec'd size). The springs brought both sides of the rear end up and the car looks much better and more balanced, in my opinion. I'm not sure that the old worn springs were the issue though, because there is still a left to right height difference of around a half inch. I ended looking it up in the manual, however, and this variance is within Mercedes' specs for rear suspension. Go figure. It needed new rear springs anyways.