I also have a 98 SC400 and now have gone through three 12 disc changers. The replacements were purchased on EBay - they worked at first and then conked out shortly thereafter. The consensus seems to be that the 12 disc changers eventually will have problems including, without limitation, error messages, incessant skipping with long drop outs, and discs getting stuck. I am now going to try the '96 ES changer, which again, the consensus, seems to be that it's a decent replacement. The later generation ES changers have error correction, which helps with the skipping. Also, they do not have issues reading CD-Rs. I don't know that any of the 12 disc changers ever had error correction, though the later models seem to read CD-Rs better than the earlier ones. I realize that the ES changer won't look as neat in the trunk, but it's better than having a non or barely functioning 12 disc changer. I plan to have the ES changer professionally installed, so hopefully it will look halfway decent. As for the 1999-2000 in dash units, I've read that they will not work with the head units from the prior model years. I don't know about the Blitzsafe adapter. My understanding is that there are no adapters that allow for the use of a different changer with the existing head unit. However, I did see that Soundgate makes an adapter that plugs into the back of the head unit and provides jacks for use with an iPod or MP3 player. However, I do not have any details beyond that. If you find out any other information, please post it to the forum. Thanks.
Get a 96 ES 300 changer and fabricate a bracket for it, The 6 disk is one of the best that lexus ever used. Again, The 12 disk changers are never worth fixing, They always fail, ALWAYS. THE 12 DISK IS NOT NAKAMICHI IT IS MFG'D BY FUJITSU = GARBAGE.