Kirk,
I think it's actually a 4.23:1, and it came in what was known as an eco-disel. I used to know the tranny code off the top of my head, but I forget (AGB?). I looked and looked for one a couple of years ago when I was running my ITB Rabbit GTI. Found one used box, and the guy wanted $500 for it. At the time, I had a line on a new one from the dealer for ~$350. I ended up buying a VWMS one from someone out in the midwest.
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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608