The Joovy Caboose S Rear Seat is a replacement seat accessory for the Caboose S. It is listed under Joovy accessories and carries SKU code 9107 in the Standard option.
The replacement seat clicked right into the frame and matches the original fabric perfectly. My four-year-old can climb in herself now, and the rear seat still folds flat with the stroller.
My toddler finally stopped fighting the stroller once she had her own seat back there, and the replacement clicked in with no wobble at all. It's the exact same seat that came with our Caboose S, so the fit and fabric match perfectly.
Our toddler's rear seat got chewed up by the dog, so this replacement snapped right on like the original. The seat pad matches the rest of the stroller perfectly and my daughter climbs in without complaining. Way cheaper than buying a whole new stroller.