CJ
The overall measurement (end of spline to cup) is 102.5mm, from end of spline to shoulder is 38mm.
All you can do with the longer axle is try but I don't think it will work, I can't try it at the moment for you as I have no 3rds assembled. Can you find a short Vit 26 spline locally to use ? I could look here for you if you like ?
I only have my front 5.83 and are waiting for Calmini to send out the rear (12 bolt type) with my Anvil, I hoping from what I've heard to have it shipped out this week.
Kinda a pi$$ off not having it running as I'm off work for a while and could be putting it to good use