You can fairly easily find this using google, as Verizon Wireless produces a description with each upgrade. For example, the first update, to 2.4.330 is here:
DROID 2 Global Update Fixes few Calling Bugs, Finally here - Droid 2
The next update, to 4.5.608, was the first release of Gingerbread on this phone. And the only other one was the recent update to 4.5.629, about which you can see a lot on this board!
Re your previous post, "Why won't z4root work? Did Moto change stuff in 4.5 that broke it? That is what I used initially without any problems..."
Simply, z4root is a Froyo exploit and doesn't work on Gingerbread.
Ahhh -- I thought there were more than just a two upgrades based on the version range (2.3 to 4.5). So the only one I need to check is 4.5.608 and that was one I did find the changelog of. Given that, I guess I will just stay with what I got for right now.
And thanks for the info on z4root. I didn't realize it was version-specific. I had used it on my DX as well but that too must have been Froyo.
Thanks for your help and patience answering my questions. Have a good evening.
Frank