Hey Jefe,
I am running LT235/80R 17 tires not any 19.5's.
I see in your signature that your running 315/75R16's which are about 3" wider and have about 2" more sidewall to work with and probably have a max psi of 50 lbs. I used to run my 1/2 tons with similar tires all over Anza Borrego. I could not agree with you more, that lowering the tire pressure is the first/best thing you can do to get through sandy conditions.
The wider, taller sidewalls certainly give you a leg up on what I have to run.
I don't think I can really ever wander the desert washes as I once did in my 1/2 tons, but I kinda new that going in when I purchased a TC on a dually. I was just hoping some folks out there were successfully getting through some sandy environments with a similar set-up to what I have.
I will certainly research the spline count so they match.
Thank you very much for your insights.
Mr. E