HI, I have old NSC p/n LM120H-12/883B and wnat replace it by new TI ordering code LM120H-12/883. But can't find differences between suffix B of NSC to new TI p/n. As i understand for MIL-STD-883 letter A,B C and cet... define revision of document. If so, wich 883 fit to TI p/n?