The 1947 - Present Chevrolet & GMC Truck Message Board Network

I have a speedometer issue resulting from installing a 350 with 700r4 where an old v6 manual once lived. I was pricing the GPS speedometer units on JEGS, so I won't have to deal with a cable or sender. These are very expensive. I recently put a Garmin GPS in my lexus and it not only is attractive, but has a speedometer built in along with many other great features. It's nice looking and I see no reason why I couldn't build one right into my dash right where a speedometer goes and wouldn't need to hook up anything. Anyone done this before? If not, I believe it will look great and be very functional with all it's advanced features. Cost $149.00. Tell me why I shouldn't do this.