Does anyone know if split tanks from a 93 Sportster will work on a 99 Fatboy?
I have a set of split tanks for sale and someone wants to put them on their Fatboy.

 

I of course may be mistaken but I don’t remember any XL’s coming with split tanks.
If yours has the stock mounting Big twin configuration for that year which is vertical tabs up front and a horizontal tab on each tank towards the rear, they should work on a Softail.
If you can post pics of your tanks it could help getting an answer to your question.

 

I also have never seem a Sporty with STOCK split tanks. Lots of them were added to make Piglets.

 

I did it years ago on a hardtail frame, but I made my own mounting tabs, and welded them on.