modern voltage limiter for dash gauges

Yeah but for cars like Vixen, that plug in version doesn't work. And I don't know why everyone uses the 7805. That's a 5V output. That's incorrect. You should use the 7806. It's 6V output. That's how you check and or calibrate the gauges. You use 6V to get them to read "half way" and "adjust" the needles as needed. Whoever got the 5V thing going is mistaken. Making one yourself is still way cheaper.