I just put on my 4th slave tonight (Mazda B2600) since my car was new...hmmm about 4,000 miles and 7 years!
Heat shield was added, fluid annually flushed with the same piss poor result of parts failure from too much heat where the master is located. A poor engineering design. Thank God I can work on my own car and the slave is only $12.99 at advance auto parts.
Never had a pushrod problem and mine is just a mickey mouse piece of threaded rod with a couple of washers...from the factory that way! (But it works).
Cheers ya'll!