Amiga 1000 system boards

[Jules Richardson]

Any Amiga geeks out there? I picked up a pair of Amiga A1000 systems a 
couple of weeks ago. Both are Revision 6 boards (going by IC dates, one was 
likely built in October of '85, the other in January of '86). However, 
bigbookofamigahardware.com claims that rev. 6 boards had copper traces and 
the later rev A board were tin - but in this case the earlier of my two 
boards is tin (while the later one is indeed copper).

Just wondering if I have a bit of an anomaly (and the above site's 
correct), of if the reality is that rev. 6 boards routinely appear in  both 
copper and tin?

s/n on the early system is 6000146, the later one is 1165109; I have no 
idea what production numbers were like (anyone?) but I'm assuming that 
there's some form of plant number involved in the leading digit(s).

cheers

Jules