We have a tech article about this,
http://www.mar-k.com/installation_hints.aspx that might help. Scroll down to "Bed Installation" and look for "Bed Side Interchangeability". The wider frame of 60-62 may be a problem if you want to use those years without modification. 58-9 had a shorter wheelbase, although the bedsides look similar, the fender is in the wrong spot for 66.
Mar-Ktech
