At around 140,000 miles my ’96 Bronco, with 5 speed manual transmission was developing shifting issues that I felt meant I was going to have to have it overhauled. From stopped in neutral it would not want to go into 1st gear, if I put into 3rd then it would slide right into 1st. Eventually shifting from 1st to 2nd at low speed was the same problem.
I heard about BG Syncro Shift II and filled the trans with it. Within a week or so I began to notice a slight improvement and after 5000 miles I had no shifting issues at all. I now have 208,000 miles on it and have absolutely NO shifting issues.