If your trans is attached to the engine block it should not be easy to spin. If it did then you should be concerned.
To address your other issue I recommend draining your fluids (both Tcase and trans) check for metallic sludge and/or excessive metal chips/flakes on drain plug. I would also consider replacing your release bearing if your RPM's drop when you let out your clutch. Keeping in consideration that it is a desert rig it's possible you have excessive sand/dirt build up in you bell housing.
P.s. replace your seals and make other upgrades and repairs while you have the trans off
