This is a picture of the (a) tie rod as used on a W124 Benz. Most of them, that is. This is not the tie rod which is used on the 4MATIC models. No, that would be this:
The spindle is different, so the outer end is different, so the rod is different (shorter). Here is where the derp sets in. The inner rod end is almost completely identical to the normal inner tie rod end, except that its threads are RH instead of LH. Do autopart stores -or even RockAuto - recognize this fact and list the inner correctly? Do they bollocks.
tl;dr: My dad ordered the wrong tie rod end for his car Friday.
tl;dr 2: Real dick move not reusing your parts sanely there, Benz.
tl;dr 3: Especially since your normal tie rod reuses as an outer end an end which is the standard inner on a W123, I mean what the fuck.