Originally Posted by Rediranch_too
I just reread your post, and guess I missed the part about the spider (caliper mount) being different than your truck.
On my truck the mounting bolt holes on the spider and the mounting bolt holes on my axle were perfect.
There are, however, 3 different bearing sizes for the Ford 9" from reading that on the TSM site. So I guess it stands to reason the bolt patterns may be different as well. I did read that there were 1/2" diameter mounting bolts vs 3/8".
Ford 9 inch
The police cruisers, some T-Birds and some wagons with
rear drum brakes use a larger rear axle bearing then the normal cars do (1961-79). The wheels are the
same 4.50 pattern. With rear discs, which were standard on: Lincoln Town Cars 74/79; Mark IV & Mark V, and available on other 1974/78 big Fords/Mercury's and 1974/79 T-Birds as an option, the wheel bolt pattern is different. Sorry, no car parts books, so I can't give particulars on what the bolt pattern was (I think it was 5.00), and what the bearing was.
Rear disc's were also an option on 1975/80 Granadas and Monarchs, same bolt pattern: 4.50, but the rear end is 8 inch. The kissin' cousin Lincoln Versailles 1975/77 has rear discs as standard, but has a 9 inch rear end. Why Ford bothered using a 9 inch rear on the Versailles, when the Granada/Monarch used an 8 inch, is beyond me.