I found out that the ARV (the strange appendage on the front of some turbos) does make a difference, but only that it gets in the way of the air filter housing, and changes the length of the tube connecting the air filter housing to the turbo.

My engine died, and the replacement engine was a rebuilt 450k mile motor. The ARV equipped turbo was a spare from a who knows what mileage motor, but it had no felt play, versus the small amount on the turbo on the motor, and the large amount on the dying motor.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...