TRS-80 Model II 68000 upgrade (anybody got one?)

Greetings! I'm looking for the fabled card that goes into a TRS-80 Model II and upgrades it to the equivalent of a TRS-80 Model 16. Eventually, I'd like to be able to run XENIX on my TRS-80... Can anyone help? I've also got a Model 12 if someone has a 68000 upgrade setup that only works with that model. In this case, I'd need the whole card-cage addition as well, as my 12 is "stock". Of course, I'd consider buying someone's Model 16 or 6000 if one was offered. But, I'd prefer not to have a third one of these behemoths sitting around if at all possible... :-) Please let me know if you can help! Thanks, John P.S. I saw schematics for the 16's 68000 card on the web. Would this card "plug-in" to the II's card cage and work? Has anyone tried building one from scratch? -- John W. Linville Bedrock Systems