Engine Control Unit - ECU
$30 - Part # 8A0 907 404 C C / 0 261 200 858. 1990-1993 Golf/Jetta/Passat.

Transmission Control Unit - TCU/TCM
$20 - 1990-1993 Passat automatic transmission control module. Part # 095 927 731 5DG 005 906-52.