I do remember the early hydraulic lock up converters. Some of them came on pretty early and you could really feel it. Seems to me we changed the spring in the hydraulic ones to change when it came in but its been a long time since I worked on a hydraulic one. Most of the ones I worked with were the electronic lock-up as I worked at a Dodge dealer from 1986 to 2011. I don't remember what year they started with the electronic lock up though but most of the ones I worked on were electronic lock up ? Ron