I have been reading around the site and need some info. I own a 1979 K5 blazer with the 203 fulltime transfer case automatic trans and a 400SB. The rear axel is a GM 12 bolt and the front a Gm 10 (I think) Anyways I know these aren't premo for axels and I also want to change the gears out since they are 3:73 (w/ limited slip) and I want to run 42. So my question is should I just change ou the entire axels to something like Dana 60. What vehicle would be used for a doner axel? (both front and rear) Any information on the idea of an axel swap or anything pretaining to it would be appreciated.