i replaced one on my 2.9 litre when it was in my BII the coil that is and it ran me $16.00 at the local parts store.... but when i had problems with mine i found a simple toggle switch jumping past my ignition relay was the only fix for the broken wire in my harness, and its still wired that way with the 4.0 litre, i looked everyday for 3 weeks trying to loate the wire and finally just spliced into the harness past the relay and then it started and ran perfectly.
been driving it that way for 7 months with no problems.