3.15 diff problems

Well, I re-installed my 3.15 diff in my 2000 E39 and have problems with my cruise control. It will work in 4th gear, but not in fifth or sixth. Here is what I have determined:
Normal operation:
In fourth, it operates as it should- Set cruise- hit brake- resume- all good.

In fifth or sixth- it works the *first* time. Set cruise- hit brake- NO resume.
Inconsistent operation:
Fourth gear- in cruise- hit road bumps or dip- stays in cruise.
Fifth or sixth-in cruise- hit road bumbs or dip- cruise stops and does not return.

Turning the cruise system on or off (so that the dash indicator turns on or off), has no affect. The car will simply not either resume or set cruise after it fails while in fifth or sixth.

A friend has a 97 and does NOT have this problem. I also notice after reading on another board that it seems as though people from 2000 on get this when they change to the 3.15. One guy even had Dinan software and was told that this was the problem- but after now what is THREE people with the same problem and we DON'T have Dinan sw, I think something changed in 2000.

My car is at dealer- w/o discussing the 3.15 of course- to track it down- I look forward to what they find and will post it.

Any >2000 or 2001's out there with the 3.15?