Will this work on my Fleetside and Styleside bed without any modification?

Yes. This cap is engineered to fit both bed styles on the same generation truck without part swaps or adapter plates.

Do I need to remove my tailgate to install this?

The cap mounts at factory attachment points on the tailgate. Removal isn't required — test-fit it in place before final fastening to confirm alignment.

Should I prime and paint this before installing it?

That's your call. The cap arrives ready to install as-is or can be prepped and painted to match your truck. If you paint first, let it fully cure before handling to avoid smudging.