Hi Trev,
the fusible links to which you refer are within the wiring loom located close to the battery positive terminal. If the links were shot then you would have no voltage at all! I cant help but feel that your idle voltage is a little low, you should be seeing around 14 volts! Check your alternator output at the back of the unit with a voltmeter making sure you put the negative probe on the alternator casing, what does it read there?

Next check voltage at the battery terminals what have you there? if you have a difference of a couple of volts then the problem is probably a bad earth connection either on the chassis or on the engine.

CheeRS, Mike