The 9300 Deere, along with the 60 and 70 series and the Versatiles, used a Twin Disc 12 speed PS.  It was a good transmission as far as relibility goes but the gear spacing and shift quality were not the greatest.  It's probably more suited to jobs where you are not shifting under load, such as running a pan, instead of field work where you want to change gears because you need more drawbar pull in a tough spot. 

The current model Deere 4wd's use a Funk transmission made in Coffeyville KS by Funk which is a Deere subsidiary.  They don't have anything to do with the 8000 series.