OK had a reply from Scott & Ron over at Sanger. Have a look under the dash about 2" along from the main harness plug (just near the hole leading up to the dash itself) is a single solid grey wire with a female flat electrical conector. That is the tacho pulse wire for your Perfect Pass tacho reading. Mines hooked up now. Works perfect.
Those guys over at Sanger are the bomb. Replyed straight away. Nice to be a member of their family? We love our Sanger