My '51 - 3100 has only one spring on the driver side of the bench seat frame to seat riser. The F.A.M. Sect. 1, Sheet 2.05 shows the spring #3698449 between the seat riser and the seat frame on the driver side but does not show the passenger side. It seems to me there maybe should be a spring in the same location on the passenger side so there would be equal tension on both sides of the seat frame? There is also a hole in the seat riser on the passenger side same as the driver side to maybe accept a spring. So, my question is "should there be a spring on the passenger side or on the driver's side only"?