See if you can find a Kingston Ethernet PCI Card - Part number KNE 111TX/100B. I used this card in my PM 6500 to interface DSL. Also used it to network to my G4 for file transfer (you will need an Ethernet Crossover cable).
Specifications:
· Meets PCI Local Bus Specification, Rev. 2.0;
· PCI 32-bit Bus Master Architecture;
· IEEE 802.3u Auto-Negotiation for Automatic Selection of Data Transmission Speed;
· Easy Migration; Single RJ-45 Port for both 10Base-T and 100Base-TX;
· Support Full Duplex Operation on both 10Base-T and 100Base-TX;
· Support 100ohm STP/UTP Cables using Category 3, 4 or 5 for 10Mbps Mode and
Category 5 for 100Mbps Mode;
· LED Indicators for Installation Verification and Diagnostic Purpose.
Download driver at
http://www.kingston.com/support/downloads/networking/kne111.asp
I got this card for free from my ISP when I first got DSL. The 6500 was running OS 8.6.
Cheers, Tom