Problem is 39 was a change over year, it could have either the older spindle, or the newer one. You guessed it, both take different bearings. I can tell you that I put a set of Volare rotors on the spindles of a mid 30s front axle, spaced them out to clear the steering arm bolts, and used the bearings that were in the used rotor. (I don't have the #s here.) I can also tell you the bearing nuts sits right at the end of the spindle, inserting a cotter key is seriously close to the end of the spindle even with thin bearing nuts.

My kit from Rusty Hope used chevy 1/2 ton pickup calipers, Volare rotors, and late 80s GM brake hoses. Mine had the "old" style spindles. Gene