I have an early 99 f250 srw and am in the process of installing some wheel spacers for some 2007 f250 srw wheels. The front axle is a 2002 and the 8x 170 spacers fit as well the acorn nuts for them. Now the rear is a different story, the spacers fit the bolt pattern although the thread pitch does not match. so im going to have to buy some acorn nuts for the spacers. Im wondering if this is a 97 rear axle or somethiing newer? what year are the threads different on a 8x 170 bolt pattern? thanks!1

 

99 through 2003ish ford used metric course thread studs, 2003 on ford went to metric fine thread studs

 

1999 - 2002 = M14 x 2.0

2003 - beyond = M14 x 1.5

M14 - denotes stud diameter in millimeters

2.0 and 1.5 - denote the distance between thread crowns in millimeters, where 2.0 (coarse) is greater distance peak to peak than 1.5 (fine)

Unlike English/American/SAE thread pitch designations, in metric fasteners, the larger thread pitch number denotes more distance in millimeters between thread crowns. In this case, it is not "threads per millimeter". It is rather "millimeters per thread." Or more precisely, millimeters between thread crowns.

 

thanks for all the info, im thinking since this is an e99 it might be a 98 model axel which would make this a 97 axle. Both tags are on the rear cover , is there a code that might reveal anything helpful?