In my youth I used to drive a J2 as a holiday job. It was a deeply unpleasant experience, noisy, smelly heavy steering and most bizarrely a back to front gear change. With 1st towards you and up 2nd towards you and down 3rd away and up and so on. Guaranteed to hinder speedy progress.
The only good bit was driving with the sliding door open in the summer.
The J4 was smaller of the two J2 was 15cwt and the J4 was 10cwt (half ton) payload . They would get stuck on a wet blade of grass when empty !! The "shed" part in title is best description of this vehicle