It sounds to me like you have an old 7 X 'AA' pack.  New 'AA's can be found up to 2450 mAh, so chances are that any 7 cell 'AA' pack will be roughly the same weight but with greater capacity.  Watch out for the configuration whwn ordering one, because you can get either a 'flat' 7 cell or two different styles of  '4+3' configuration.

Bruce