Ford was known for doing weird shit back in the day.
You used to be able to go to a car lot and look at two identical trucks from the same manufacturing plant, that were produced on the same damn day with the same options and the bracketry would be totally different LOL!
What could really be going on is your truck is more then likely a late year production model. They could have said "hey this is a better spot", started using the location late in 86 and kept it there for all following years.