You've never mentioned whether your truck is the original 6 volt or 12 volt. If it's 12 volt, there's a possibility that someone has swapped a 12v armature into a 6v starter. There's a difference of about .03 inches which would account for some of that play you mentioned
on the shaft bushing. Your starter appears to be a 6V (at least the housing) as evidenced by the black Delco-Remy tag on it. I don't know if swapping armatures is even possible, but worth looking at. There's some good info
HERE on the differences between 6v and 12v flywheels and starters. They have to be matched up (a mismatch will tear up the gears.)
