I did a stint as a reliability engineer in the past. I would be hesitant to change anything at all in these servos. What looks like a quick fix by substituting what seems like a similar part could be changing a fundamental engineering requirement and will most definitely change the characteristics of the design. My guess is MB has tens of 1000's of hours of reliabilty testing on these since they are a safety component, your substitutes will not. Seems pretty iffy on something as critical as a hard link to your throttle.

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)