The size given by Judge (12 x 1.25) and the picture lead me to believe this reamer is nearly identical to a 1/2" reamer. My Machine Shop Supply catalog lists the reamer for $13.20, though it doesn't have the threads or hex for the fingertips. If wobble (misalignment) isn't a concern, one can save some money by using a standard reamer.

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95 E320 Cabriolet, 159K