A few years ago I bought my father in-law's 85 El Camino. He was going to trade it in on a new truck. It was too nice to let go. About a year before I bought I helped him replace the worn out 200R4 tranny with a rebuilt TH350. Since the changeout the speedo has always been off. Should I change the speedo gear to one for a TH350? The car still has the 14" rally wheels, so I do not think the wheels are causing the speedo difference.