They are completely different boats, as shown at this site:
Introducing the CAL 35 Yacht (1974 Print Advertisement)
(click on the Cal 39 at the right for a brief view of that boat)
The 35 is strictly a cruising
boat while the 39 is a typical 70's
racer cruiser. The 39 will be much faster and more agile with its fin
keel, but has more
draft that will limit you in the
Bahamas for example. The 35 probably has more room below despite being 4 feet shorter and is designed to be a cruising boat.
Also there is a rather technical discussion of the 39 here:
http://www.cruisersforum.com/forums/...-39-a-657.html
I chartered a 39 in the BVI's many years ago. At the time, it was a fun, fast boat but if I had one and wanted to
cruise on her I would make a lot of modifications. As I
recall there were a couple of different
interior plans. It probably has enough
displacement to be a decent cruiser for a couple with occasional guests.
If you like the 35, I would suggest doing some
research on the
Freeport 36 built by
Islander and designed by Robert Perry... it's a much better boat IMO. Here's a nice one that apparantly changed hands recently:
Islander Freeport 36