OEM Tach Expert Required

[Nanook]

I recently purchased (separately) two factory tachs, but as you can see in the pictures they are quite a bit different looking.

The one with the red line tabs is supposed to be for an eight cylinder and the other for a six.

The six-cylinder tach is connected differently from the eight-cylinder in that the + side is connected to the coil and the other terminal to ground, whereas the eight-cylinder is connected with the + to 12v and the other stud to the coil with the third terminal being grounded through the case.

Has anybody else come across something like this? Thanks

[Ken Cook]

I just sent my cluster off to redlineg.com . He is the one in Tennessee, not California. He is very knowledgeable about these tachs and gauges.

[Nanook]

Thanks...I will follow up on that