first number (4) = number of forward gears.
second number (6,7,8), heavy duty/weight rating 6=1500, 7=2500, 8=3500/diesel
R = not sure.
H=hyrdraulic, E=electronic

46RE, 46RH = 1500
47RE
48RE

 

almost corect, 2nd number is load but determined by vehicle drivetrain.
5.2-5.9 1500/2500/3500 have 46 series trans
v10 and cummings 2500/3500 47/48 series trans

 

A 727 pan isn't deep enough, even a deep sump 727isn't deep enough. The larger valve body and shift seleniod hang down too low.
Now, certain deep sump pans listed for 727/46re trannys will work, and are usually listed as to the amount of extra fluid they'll carry based on the model tranny.

 

The (R) stands for "Rear Wheel Drive"!!!