Overdrive for a 454?

[rs74]

My 84 K30 has a really stout built 400 trans in it but I am want to know about an overdrive. Is there an older 4l80 trans that could be swapped in with little difficulty. Were they all computer controlled? I don't want to get into having a stand alone unit. If I have to do that then I might as well look into putting in a 8.1 vortec or switch to a 24 valve cummins with an auto O/D trans.

The 454 runs just fine just want an overdrive in it. I am getting rid of all my newer trucks and going back to driving the older models and it is just kind of weird having a three speed trans. I keep waiting for it to shift. A bit more on the mpg's wouldn't hurt either if that is even possible.