I have a 92 D150 with the 5.2 318 and 518 automatic, the trans was changed under warranty years ago by Chrysler, A few years ago I pulled the trans and had a Mopar Performance shift kit installed it made a big difference and shifts hard 1st to 2nd. I was going to buy an aftermarket convertor for it but Lenny at Ultimate rebuilt my stock lock up convertor and increased the stall speed and I picked up a little over a tenth in 60ft times. From 2.20s to high 2.0s with a best of 2.05. btw truck runs consistent 15.20s in good air 30s in heat.