300 TDi alternator change question

Hi Folks,
I'm hoping someone can help a newbie out with some advice.

The alternator on my defender 90 300 tdi (98) has packed in so I've bought a std 65A replacement. However on receipt I have found that the pulley is a different size and there is no fan fitted. I guess this is because the alternator can be used on multiple vehicles.

Unfortunately I'm having problems removing the large retaining bolts on both alternators so a swap is not the simple job I was hoping it would be.

I therefore wondered if there would actually be an issues with just putting it on as-is. If the fan isn't supplied does it mean that it's not always required ? also, does anyone know if the different pulley size would cause an issue ?

A picture of the two is attached.

Thanks in advance,
Richard

A windy gun will have the nuts straight off, I was struggling with mine and it had them straight off.

most 300 tdi alternators dont have external cooling fins,ive put a 300 alternator on my 200 disco just had to swap the pulleys.

thanks Guys. I thought the pulley might have to change. Unfortunately it still means getting the damn nuts off and I don't have easy access to windy gun !

all the best,
Richard

large alan ke swan neck spanner should do it