According to the manual: http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm1208.htm
About the middle of the page. Max charging current is 40 Amps. So my "opinion" is 50 Amps for the gauge. Same as the GMC but different color. That would be the "internal" shunt rating. The meter movement is as fragile as any other.


Steve H