You have a chain-adaptor kit on the bike, that replaced the original belt drive. You need a front sprocket, rear 70 tooth sprocket, and likely the original front sprocket nut and retaining hardware. As well.... you'll need a belt, and a primary gasket kit, since the inner and outer primary will have to come off to replace the sprocket and install the belt.
According to your year/model, you'll need a 136 tooth belt.
(Fits 85-96 FXR, FLT, FLHT, FLHS, & Road King models with 70 Tooth Rear Pulleys (Replaces OEM# 40001-85)
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