Since you didn't say what model MB these are going on, I can only seem it is the 123 series since you have an '83 300D in your signature.

With that assumption, this is a pretty simple installation with only two tricks I can offer.

Before the tricks, the shock gets a cupped washer with the cup toward the bushing. It goes through the top hole then the other bushing over the shaft, then the cupped washer, then the nut.

The two tricks are; first you do not cut the strapping from the shock until you have bolted the shock to the lower control arm. After it is bolted at the bottom and you have the lower cup washer and bushing in place, you cut the strap and guide it into the upper mount hole as the gas pressure causes it to extend.

The second trick is to have both front wheels safely off the ground so you can turn the wheel lock to lock to access both lower bolts that hold the shock to the lower control arm.

Good luck,