What ampage alternator do i need for 1600 12v ?

Ampage only depends on the electrics you are running not engine size

Generators will usually cope fine, so I suggest go for a lower ampage one, unless you are driving a lot at night with spots on you wont need any more. Compared to a standard Beetle we dont really use much electrics

There are exceptions but generally
   We dont go out in the rain so no wipers or lights
   We dont drive much at night so no lights
   Many of us dont have radios
   No interior light when you open doors or accidentally leave switched on
   Many of us have fitted LED brake and side lights which reduces the power needed even further.

So, are you fitting loads of high drain gadgets?  If not just a low ampage one will do or stick with the genny and save some wiring

Dave

Unless big stereo with an amp, or significantly uprated headlights, I would look at cost over amps in this case. Buggies just don`t have enough electrics to warrant high output alternators. Basic is usually fine.

Changing as mine has a lot of play in the shaft sideways and backwards/forwards and a rumbling sound do they all have internal regulators ?

No, some have an extra three spade terminals on the top for an external regulator, and some have internal regulator.

mine has a single spade connector and threaded bolt for i think the live

Thats one with an internal regulator