Help 1986 300SDL What size alternator?

[Mr. G]

My alternator went south. Front bearing/bushing is shot. Ths shaft is wobbling and making all kinds of noise when running.

Auto Zone has lifetime rebuilts @$102 for a 55 amp and $170 for a 70 amp. They say that it's the same casting, just one's more powerful than the other.

Is there any reason I need the 70 amp. I am not running any unusual accessories in the car.

Thanks