Nicke123

I’ve dropped in 2000 VT commodore v6 3.8L ecotec motor. Into a 1996 Hilux solid axle which had the 22r 2.4L petrol motor. I bought marks 4wd wiring harness. But does not include tacho kit. I have a saas tacho gauge I can use if I can’t use genuine. Just wondering if it is possible to wire up or do I need to buy marks 4wd tacho kit for it to work? If so where do I tap into the signal wire? And do I need to use a special negative or can I use any negative? Can someone please help me. Thanks