it is actually for a ford rearend, but the principal is the same for ring gear centerline (i only wish i could change the pinion shims as easy as on a frod)
add/divide/subtract/combine to get pinion depth from bearing centerline $20+math is better than $400+lazy. wish i could be lazier but it's not like i do them everyday.
i s'pose i could easily get that measurement off by as much as .001", but it makes a good starter to bolt things together w/out breaking anything, and to measure the tooth pattern.
$20+math is better than $400+lazy. wish i could be lazier 
but it's not like i do them everyday.
