I think if you do a search here, you'll quickly discover that the older cruise systems hardly ever have a working amplifier, and the cost to repair or replace is way more than an aftermarket 'add-on' cruise system anyway. If I were you I'd forget the transplant. The odds of it working even if it is hooked up right (a major exercise itself) are stacked against you, and if it doesn't work, you'll have a very hard time figuring out if it's something you didn't connect properly or if it's a bad component in the donor system.

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1986 560SL
2002 Toyota Camry
1993 Lexus