Safe "Drive" Conditions

[JimRummy]

Just a quick question, what are the acceptable terms to use the (D)rive and (OverD)rive, and by this I mean is it safe and alright to drive freeway speeds (and a little higher {60-80}) with the transmission in Drive? I know that OD is what should be used, but I have been having some issues with OD, and I don't have the means to address them (I think OD is causing some heat issues). That being said I just need to know is it is okay to drive the truck without using OD.
I do drive a 120 mile commute about 2 or 3 times a month, and there is a large grade both directions...It is a 93 4.0 V6 AT 2WD by the way.
Let me know, thanks guys.

 

[exbass94]

You can go as fast as you want in Drive and not damage the transmission at all. Keep the engine RPM at a reasonable level (I would shoot for 3500 RPM or below) and everything will be fine. Your gas mileage may suck but you won't hurt the truck at all.

 

[aspevacek]

The heat issues caused by the truck being in OD would most likely be the Torque converter.

Does the transmission hunt for gears while it is in OD and you hit an incline? As in you feel it repeatedly swapping in and out of 4th gear?

 

[JimRummy]

Yes it does. When going up a large grade it does. I have to put the pedal down to force it into 3rd so it doesn't bog down, like it wants to stay in 4th. It also clicks loud, and very quickly while under a load (and generally only clicks under a heavy load like a large hill) coming from the engine bay...