Only the large bolts at each end were (are) Ti... except when those were made from aluminum. The "story" goes there was a cold-war western hemisphere shortage of titanium, and so (like steel replacing the copper used in pennies during part of WWII), Campagnolo switched to aluminum as a substitute. Seems to have been around '80-'81 IIRC.
Not having researched (googled) it... Seems likely as a reason, given the US-USSR friction at the time. Switched back to Ti for the rest of the SR run, till '87, (the RD with no markings on top). I remember the first one of those I found, thought it was some sort of prototype.
Cheers, Eric

Now if someone will just send me a pair of those Ti hubs, I'll be all set...