I pulled the OD off this afternoon to have a look.
Here's what I found with the snap ring. It was was present and accounted for but had popped out of its groove. As soon as I touched it with a screwdriver it and the washer fell right over. Not good.

The bowl gear had loosened considerably but had not come completely undone, hence the mainshaft slop. Talk about playing with fire.
I got on the horn with Advance Adapters and learned a couple things. After I brought the tech up to speed on the past few days' events I asked how I could better prevent a $6 snap ring from wiggling free and destroying an entire Jeep. He told me that the snap ring "batches" vary depending on the composition of the metal alloy used. Some have better spring tension than others and, as a result, some are more prone to coming loose.
Holy cow. Not exactly a comforting statement.
He also informed me that the snap ring design itself was overhauled and beefed up roughly 3 months ago. Since I happen to have another brand new Saturn in the box that arrived last week, here's a few pics that show the difference between the "new" style snap ring and the old one ("old" as in one that came with this OD when I bought it new at the end of 2015). There's no question the new one is heavier and appears better suited to stay in place. That also means it was a real bear to install but I did get it in there.


And as for getting them seated - I am certain I did it correctly the first time. After I install these snap rings I always use a screw driver to rotate them 360 degrees in both directions so I can verify all corners of it are firmly seated in the groove.
I have struggled in the past to torque the bowl gear to the specified 100-120 ft/lbs and still have the tabbed washer line up but I was able to get it to just over 100 ft/lbs this time. AA tells me anything over 100 is sufficient (but don't go any higher than 125 ft/lbs) while Herm says anything over 75 ft/lbs is good enough.
When I installed the new snap ring today I did discover a bunch of metal shavings in the groove, presumably ground out by the old snap ring making its exit. I don't know what permanent effect this had on the groove and there isn't much I can do now. I cleaned it up and put everything back together.

A test drive around the neighborhood shows improved shifts from 2nd to 3rd but there is still a slight crunch. It does not crunch if I double clutch. Obviously I inflicted damage on the 3rd gear blocking ring driving and shifting with all the slop in the main shaft over the weekend. How I made it home at all is nothing short of a miracle. I mentally calculated about 4 different routes to make the 25 mile journey home Sunday and took the one that I knew would require the fewest 2nd-to-3rd gear shifts. I rounded a couple tight turns nearly on two wheels in 3rd gear to keep from having to shift and relied heavily on the OD where I could to compensate. Not sure how much longer I had before the OD completely came apart but I'm very thankful it didn't.
It's ironic as Oilly and I have another thread going about these OD snap rings here (
http://eastcoastwillys.proboards.com/thread/1693/overdrive-failure ) and now it rears its head on this forum under what started out as a completely different topic on an entirely different Jeep.
More testing and research is definitely needed on these snap rings (and/or a better overall solution) I'm just hoping for minimal destruction in the meantime.