The following substitutions from the SIPLUS extreme product range have been available since 09/2009 or will be available as of 10/01/2011 for S7-300 SM326F DI24:
6AG1326-1BK02-2AB0 replaces 6AG1326-1BK01-2AB0
6AG1326-1BK02-2AY0 replaces 6AG1326-1BK01-2AB0 (for 'rolling stock')

SIPLUS extreme represents the product range with refined components on the basis of Siemens Industry standard products.