thanks for the follow up guys,

in reconnecting the new Alternator, i noticed to the original there were 2 black wires joined to a single terminal onto the back of the alternator yet the new one doesn't have anywhere to connect this to. do we know what these do? i did run the car with the wires on the alternator and without and no difference so not sure what they are meant for

i run the multimeter over the alternator at the rear and was only getting a reading of 1.6 so im wondering why if its a new alternator the why would i be getting such a low Reading? if the reading was high i would presume a problem back to the battery but seeing as its from alternator a mystery.

i did have a thought about the belt slipping, but cant see or hear any evidence of it happening,there is no squeaking or anything.
ill try replacing the earth wire from battery, i did look over the earth wires and no signs of damage but it was dark so ill look again.

thanks again guys