i have an 89 s10 blazer and when i put it into park it does not go all the way into park like it is on park but is still half way into reverse i can start it and it will go backwards how do i fix this

Check the shift linkage and shift arm at transmission for play or being lose.
If that is all ok then check.

The shift rod from frame to shifting tube arm will have a sliding adjustmet on it.

With shift lever locked in park adjust it so the transmission lever is locked into park.

And make sure it will not roll with transmission lever in park position.

I have had the shift lever and lever plate inside transmission come lose.

thanks ill give that a try