In a message dated 4/30/02 9:34:23 PM, KCTOMMY@msn.com writes:
<< 653 is supposed to be similar to 853, but lacks the heat treating. >>
I think that 631 is the non- heat treated companion to 853. 653, as I remember, was touted as a non-heat treated version of 753, but was more like a lighter guage version of 531.