I think what Julia demonstrated was some sort of aftermarket contraption that sat on a pan on a rack, the motor at the front side, but closed inside the oven. It seemed very clunky. If her oven had a rotisserie feature, I'm sure it would have been incorporated into the design. But Julia was very big on demonstrating attainable equipment, so she would have used an in-oven rotis. that anyone could have bought, rather than demonstrate the fancy features of her own oven.
My mom's GE wall oven has a rotisserie motor built into the back wall of the oven cavity--you just flip a small cover to the side and the fitting for the rotis. skewer is behind it. When you turn the selector to ROTISSERIE, you can hear that motor grind to life and the broil element is what cycles on and off. We've never used it as the skewer, holders, and stand were gone when the oven came our way.
T.