Probably not worth it for the labor involved to just replace the boot. Best bet is to replace the whole balljoint.
It would be difficult to get the old joints really clean, and if they are making noise, that is a bad indicator in terms of condition. They are only $15-20 each for the part. If you do not have a press, they can be knocked out with a good vise and a big hammer.
1986 300E 5-Speed 240k mi.