Overdrives based on the 727 are called RH46 and RE46
Rh is hydraulic governor...RE is Electronic governor that is shifted by the PCM...
Overdrives based on the 904 are RH43 with the H being Hydraulic controlled governor.
We never used the designation RH46 or RE46 - it was 46RE or 46RH. We went to this designation after program launch - at launch they were called 500's, 518's, 618's.
We never ever offered a 43, only 42 or 44.
The PCM doesn't "shift" the trans - it only controls governor pressure on the RE units - the valve body shifts the trans between gears and in to OD.
On the RH it only controls the OD.
Splitting hairs - not really - any of these transmissions will shift manually in to each gear except OD.