Oil for 3-speed?

Changed out the 3-speed non-synchro-1st trannie fluid today (A903). The old fluid was clean and appeared to be a 75W90 wt gear oil; not too heavy. Put in Mobile 1 synthetic ATF, compatible with Dexron, DexronII, DexronIII, Mercon etc. Seems to run fine and as quiet, perhaps it shifts a little better. The shift out of 1st gear when moving is not hanging quite as hard now.