Without doing any research on the topic, I'm going to go ahead and say no, nobody offers an aftermarket arm. It's a complicated stamping that has two attachment points to the subframe, is the carrier for the wheel bearing, is the lower spring perch, and lower shock mount, is the lower sway bar link mount, as well as the mounting for the rear brakes. Unlike some other suspensions that have adjustable links that adjust camber, yours has no such links. Camber is corrected by correcting the ride height.

__________________

90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff