Correction, mine had the 700R4. Thanks for the reminder Swamp. I think they are the same thing as a 4L60E actually. I think eventually they figured out how to make them reliable with the big diesel. Just took a bunch of experimenting by the after market guys and poor fools like me trying to fix what GM shgould have done. More clutches in the 3rd gear pack, better band, better servo, better pump, revised valve body, better torque converter (get the commercial one). That motor had so much torque just off idle, the old gas transmissions just weren't ready for it.
At least I learned how to rebuild automatic transmissions because of them. Note to self: I don't want to have to do that again!