What is the difference between a 3 connector and 4 connector starter relay under the battery? I have a 3 connector and can only find a 4 connector on Ebay.

 

The 3 connector one gets its ground through the mounting bolts, whereas the 4 connector one needs a wire run to it for the ground.

 

If your buying a brand new one it will tell you witch three post to use,you just dont use the forth post.

 

That is what I figured. There had to be a reason why they don't make 3 connector relays anymore. Thank You All!!