George, were the 3.15 and 3.85 diffs different lengths? Did you have to modify the driveshaft again when you switched?
On my 6 mt the front half of the m3 shaft ended up being 673 mm from center bearing to guibo face. Put a couple hundred miles on it so far. Theres a slighy wobble but we're trying again. I'm actually wondering because the m3 manual shaft on realoem is only a couple mm from my final driveshaft length. Not that it matters because they had to re-tube it to switch the tri-flange, but just wondering if I'd have bought the m3 manual shaft if this would've been easier...