The seat on my 1954 Simplex truck is identical to the seat on a 1950 Harley servi-car that i am restoring - i will post pics tomorrow but these seats are a few inches wider than the two wheeled Simplex and have 4 ribs on the bottom side rather than 3 ribs on the two wheel bikes. Even the repop single seat for harleys is the same so I am pretty sure Simplex used the same seats during that time period that the trucks were built. I will also post some measurements. just a little fyi.
