89 Dakota. 2WD 3.9 V6. All of a sudden while exiting Home Depot with a bed full of mulch, the forward Drive gear felt like it went into neutral. No forward gear in D, 2 or 1. It does work in reverse no problem. Towed home. Can a bad tranny speed sensor cause this? Are these trannies A500's? No codes stored. Fluid level good, color good and smells like it should.