Standard Motor Products list this one

STANDARD MOTOR PRODUCTS Part # TH35 {THROTTLE POSITION SENSOR

for your '96 E350.

I found the listing at Rock Auto. http://www.rockauto.com/

Just do the parts dig down for your model and you will find it in the Emissions section.
Click the blue "i" for information and you can veiw three pictures of it to see if it is like yours. It's the sensor only, not the complete pedal assembly.

Gene