Since this thread has been revived, I'll suggest something else to all of you. Do oil sample analysis of the trans fluid too. I did with Blackstone the last time I changed it. Their analysis was that it was a little high on some metals, but that I needed to do another sample next change to start to establish the baseline. The oil plug had some fine fuzz on it, but no chips. That's about what I'd expect for a manny tranny with synchros. Synchros do wear and produce fine fuzz. I'm coming up on 80,000 miles.
I have already gone to extended engine oil changes based on oil sample analysis (10,000 miles). I plan to do the same with transaxle fluid, based on the results of the next change (due around 90Kmi.). Unless some EP components are degrading, I don't see why the fluid should be changed every 30Kmi automatically.