Been looking for tanks on eBay. From the pictures 5 gallon look

the same as 3 1/2 gallon. Are 5 gallon higher, wider, or longer

than 3 1/2? Anyone know of a site that gives the dimensions

of 5 and 3 1/2?

 

The tanks mount exactly the same way. The 3 1/2 are approximately 15 inches wide. The 5 gallon are approximately 17 wide measured at the gas caps. The length and height are the same. It's a matter of taste on what you want. The 5's look all right on a bagger but look out of proportion on a FX style bike.