Had the engine check light come on in my 1998 RAM 1500 SLT 2 wheel drive with automatic transmission. Code reader said it was a PO720, speed sensor. I reset the code but it came back the next day as soon as I drove it. Picked up a new speed sensor switch at Advance Auto for $21.95 today and replaced the one in the transmission. Not too bad a job, need a 1" deep socket or a 1" wrench, and I had the new switch in hand when I removed the old one so only lost a few drops of transmission fluid. Reset the code again and took it for a test drive and no check engine light so it looks like a new speed sensor switch took care of the problem.