Is David bowies bulge in labyrinth real?

I've heard some sources say it's fake and its a puppet or a strap on or some shit like that...then I've heard some sources say david bowies dick is actually that huge and that ken Pitt said its like the pendulum of a grandfather clock (I dunno how big a pendulum on a grandfather clock is becuz the clocks come in all different sizes). I'm confused? Is it real or fake?