Thanks for your reply.
My old alternator lasted 64000 km. Sorry, my car is on km rather than miles as I am on the other half of the world!
It was factroy fitted in 1992.
They did not test the regulator nor did they rip apart my alternator. Out here where I am, they don't tend to have any re-conditioned parts and thus everything is new. Mine was a brand new Bosch 120 amps.
Bottom line, was I dumb in replacing with a 120 amps and should I have gone with a 150 amps? Also just again, anyway to test if there are any spare capacity on the existing alternator output? I am hestitate to use the "cool harness" as the fan will draw 35 amps which can be a bit harsh on the electrical system.
Your advice is very much appreciated. Thanks again.