>Be very sure to use limited > slip length axles with limited slip rears and vice versa. Axle lengths are > different. There is one clinker in the soup: In 1964, and 1964 only, all axle lengths are the same. It makes no difference if you had a locking ("Sure Grip") or non-locking differential. In 1964 all axle lengths are the same, at 31.5". These 31.5" long 1964 axles are the same axles as used on Sure Grip differentials 1957 through 1963. The axles for non-locking differentials 1957 through 1963 were 31.625" long. There are no distinguishing marks or differences between the 31.5" and 31.625" axles and it takes careful measuring to tell the difference. If you were to take the axles from a 1964 non-locking differential and throw them in your 57 - 63 non-locking differential, you would regret it. You would have .250" clearance for axle end play, and no amount of shim removal will compensate for that. Service Manual Errors: It has been noted in previous posts that the 57 service manual has an error in the axle clearance specification. This is not the only error in the 57 service manual. While restoring my 57 Saratoga, I found numerous errors in specifications and wiring diagrams. I determined these were indeed errors in the manual by checking the 58 service manual.....and also by the fact that reality didn't match what the 57 manual stated. My point: get yourself service manuals from other years. When something doesn't make sense, check the other manuals....it is entirely possible that an error in one manual was corrected in the manual from the following year. This seems to be especially useful if the car you're working on is the first in a new body style, such as 1957, 1960, 1963, 1965. RRRRrobert of Golden Lion Grrrages www.simplexco.com/auto