You want a 30-0-30 ammeter. Available from Farm stores if not auto stores. You can hardly see 10 amps charge rate (and my MF-135 peaks at under 20 amps) on the 60 amp full scale meter. There are at least three variations on gas gauge systems. The meter and the sender need to match or you are better off with a wooden stick poked down through the open gas tank cap. Some go in opposite directions. Some are low resistance for full, some are high. Some have a minimum resistance different than others an some have a different resistance range. There's only "universal" when the meter and the sender match and the sender is adjustable for tank depth and mounting. The tachometers for cars tend to expect idle speeds where tractors run at full load, so the display gets compressed. Seeing the difference between 1500 and 2000 RPM (min and max working speeds for the MF-135) on a 0 to 12,000 rpm tachometer leaves a whole lot to be desired. If the old gauges work, why replace them? They are selected to match the needs of the tractor. You need a tach with 2500 rpm full scale. Fast idle on a big racing car engine. I have seen a digital tach with 10 rpm resolution, most are 100 rpm resolution. And then you loose the reference for 540 PTO speed which can be important to the use of PTO power implements. Too slow and they won't work well, too fast and they fly apart. But the digital tachs won't fit the MF-135 dash opening. Its too big. Few if any automotive tachometers allow for three cylinder engines and electrical drive. A mechanical tachometer also has to allow for differences in the drive source (camshaft, crankshaft, governor shaft, generator shaft) speed and direction. Gerald J.
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