Jamie, that tid-bit of info I gave you was givin to me straight from the man himself over a phone conversation. I had just blown a bearing retainer in my crawler a day before TO and I was to lead trails the next day. In desperation I posted on Marlins board begging for any help I could get. I received a call from Marlin within the hour, as he was on his way to TO as it was. I beleive what he said was "you mean you have access to a 23 spline box" Yes, I said "well go to the junkyard, get yourself a top shifting V6 T-case from a 95.5 - '04 slap it together and you have just upgraded your drivetrain" ..Something along those lines.
I beleive the reason for the 23 spline 3.4 being stronger than the 26 spline 2.7 is because even though there are less splines the 23 spline has a larger diameter shaft..
Whether it is worth it to upgrade your T-case or not is up to you, depending on how hard you're wheelin' and if you're going to run over a 37" tire. I wheel the living shit out of my junk on 37's (maybe 39's soon) and I had what I needed to upgrade so it was a no brainer.