I have an '86 also and had some starter trouble this year. I think it was Jim who told me to make sure the solenoid was solidly grounded. Mine is mounted on the block. It was very rusty and not making a good connection so I sanded it (see pic). I also replaced all my battery cables. I would make sure all the connections are clean and rust/corrosion free before buying a new starter. Al bad connection can cause all kinds of problems.