The Macintosh Display Card 8*24 GC (M0122LL/C) has always had PAL capability.
The current ROM version is 1.1.
On the other cards, there is no visible difference (8*24 M0507PA/B; 4*8
M0121PA/B). The only change is a ROM revision.
Apple introduced a new ROM for the Macintosh Display Cards 4*8 and 8*24 in
July. The card uses sense-pin combinations to determine NTSC or PAL. We ship
all new cards with this ROM (version 1.2, part number 341-0868). You can get
upgrades for older cards (fee involved; see the August Service Mailing).