The Workshop Manual section 32.6 shows that a specific distance 'a' needs to be maintained from the end of the bolt threads to the upper edge of the hexagon screw nut. Section 32.0 specifies 'a' to be 23 +/- 1 mm. This is the manual covering passenger vehicles starting August 1959 (the pages in question show "Modification Oct. 63")
What compounded this specification was that the original setup had a second thin nut serving as a lock on the main nut, but the replacement kit from MB came with a nylon lock-nut, instead of the pair. (a similar change occurred on all shock mounts). This would obviously affect the distance 'a'.
From my recollection, the replacement threaded link rod from the MB kit had been designed in such a way as to require the nut to be tightened in all the way until the end of the link rod threads, no matter how compressed the rubber gets. Measuring the length of the rod threads should give you a quick sanity check.
For reference, the specifications given in Section 32.0 are as follows:
Torsion Bar Fastening on Lower Control ArmModels 190 c, 190 Dc, 220 b, 220 Sb, 220 SEb, 300 SE, 230 SL
| Rubber Buffer Part No. | 111 323 00 44 |
| Rubber Buffer Height | 28 mm |
| Rubber Hardness Shore | 50 +/- 5 degrees |
| Hexagon screw length | 200 mm |
| Spacer tube length | 68 mm |
| Distance 'a' from screw end to upper edge of hexagon screw nut | 23 +/- 1 mm |
Hope this helps.
