Could be a shaft. I have the same thing, and my shaft is very loose.
'81 Mark VI 2 door
'88 Towncar Cartier
'07 P71- steedas, jmod, 410s, Mo's tune, numerous interior exterior mods.
'08 F-450 Powerstroke DRW: DPF,EGR delete, AFE intake Spartan powered.
RIP 94 P71, 97 P71, 99 M74, 03 M74