Hi guys and gal's. I have been talking via phone, fax, email and in person to a lot of diff builders. 2.5 years later and I am pulling my hair out. After giving up on an m78 and going towards 9 inch, I have thought maybe the best option may be an m80 or m86. Do you know of anyone who has put either of these into the older X series cars and had a decent builder. I can go on about builders and problems with people, materials used and pricing but that would take a loooonng time. Just got my "estimate" from Superformance for $6717 , ad brake lines, paint,uni bolts, and diff U bolts comes to $7282. All for a low power 302 /5LT. ANYWAY, I figured the m86 would be fine and would probably take 31 spline axles and a Harrop truetrac shortened to 1515mm or so. Has anyone got advice or a story to tell re these diffs and fitment?