I used my beta 2, 3, 3.5.. 3.5 again, 4 install on retail. There was a small patch and that was it. If you don't use the retextured zone files, there is very little you would notice different.. such as no PoK books.
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++[>++++++<-]>[<++++++>-]<.>++++[>+++++<-]>[<
+++++>-]<+.+++++++..+++.>>+++++[<++++++>-]<+
+.<<+++++++++++++++.>.+++.------.--------.>+.
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