tr Jaguar XJ6 ECU Up for sale is a Working, in excellent condition Jaguar XJ6 ECU. Part number-- DBC 3713 (DBC3713) Lucas part number 84741B. This unit is out of an XJ6 not sure what year/engine. your best bet is to match the jaguar part number up with the unit you are replacing. This is one of the most common no start or random stalling problems with these Lucas ECU's. If yours does not have this problem, keep an extra ECU in the trunk, you might some day be glad you did... These units now have to be special ordered from most dealers new for big $$ (often times over $1000!), and finding a good one second hand is getting to be a very hard chore.