Disconnect your batteries & locate the ECU wiring harness under your master cylinder. I'm not sure, but I think it's either a 10mm or 8mm bolt that holds the harness to the ECU. Remove the wiring harness. Go under your steering column & remove the 2 bolts for the cover that holds your ECU in place. Pull your ECU carefully out of it's location. Remove the cover from the ECU. There's a plastic cover, about 3/4" x 2" on the ECU itself. On that cover, there should be a label that'll tell you what your computer is. It will always be 3 letters followed by 1 number. For example, mine is PMT2. Hope this was useful.i have a 1999 7.3l psd is my computer a VDH2?? my truck is a early 99 also..