Ford AOD transmission, explanation needed please

[Limey57]

OK, so I've got an AOD (not AODE) behind the 302 in my Ranchero and I need a bit of help to understand how it works!  Talking to a few "experts", they tell me it is "P, R, N, OD, D, 2" and that under normal driving you use "D" and shift into "OD" when cruising on the freeway.  Is this correct?  I know my friends mean well, but sometimes their level of expertise is questionable!!!!! 

Thanks

[canadian_ranchero]

if you have the tv linkage set up properly,you can leave it in od all the time and it will shift into od at about 50 mph.the trans works well with a 3.25/3.5 axle ratio

[gasman826]

PRND21...fourth gear/overdrive completely controlled automatically by the transmission.  Some aftermarket valve bodies give driver control of all four gears.

[Limey57]

That's great, thanks.

[jumping jack flash]

Gary, the only time you would want to drive in D , is when you have an exceptional load . Examples are like towing home a project 57 Ford with your trailer. You would want to not use O.D. at this time. Another example would be if you are completely empty, but driving to the top of Pike's Peak. These are heavy loads for the transmission and jumping in and out of 4th gear back into 3rd will damage it very quickly. Around town or on the freeway O.D. is correct, but not with heavy loads.