I got the York of off a Grand Waggy and was wondering if the pully is the one I will need for a 79 258. Or will I needa differant pully?

No Offence, but if you cant tell if the belts are the same you will have a hell of a time mounting this compressor.
If the York came off an Older Waggy than it has a V belt pully. Eather way it does not matter My Yj does not use V belts but my York did. So I went to a salvage yard, pulled a V belt pully that would fit, redrilled the holes and mounted it behind my fan.
Works Great.
If you have a limited understanding of mechanics then prehaps you should go to Kirby's OBA and buy what you need. Then get a friend to help you install it.
Like I said no offence intended.

:flipoff2: :)

No offence taken I have had my Jeep for 22 years put a new body on it and just finished putting a new matkins frame under it. The York and my motor both have V belt I have heard that some of the pulleys have a different off set. I will be getting the bracket from Kilbey and was wondering what else I will need.