Thank's Whitedog, struggled to get 8 LUG wheels that I liked, tried wheelsmiths they didn't have any so decided to use the wellers which came on truck, filled up holes n smoothed em off pleased with result
So there is no way to pull up a part number, in the Master Parts Catalog, for just the COE or the Standard Cab seat riser. But you are correct that the illustration on the left is for COE. Check FAM Section 1, Sheet 3.01, Underbody & Dash & Toe Panel instruction index, Models 5000 (COE) Are all the Unison seats the same? There must be different shaped seat risers, one for the COE and one for the Standard Cab.
Attached is standard cab, Underbody & Dash & Toe Panel instruction index 3100, 3600, 3800, 4000, 6000 series Sorry I have no scan of Underbody & Dash & Toe Panel instruction index, for Models 5000 (COE)
My understanding is all the 1954/55st Unison seats are the same.
The regular cab seat riser is prepped/marked for (has the appropriate holes for) the Unison seat. And, the rear of the cab is drilled for the "hangers". Holes have to be drilled in the rear of the seat riser, but the locations were "dimpled" at the factory.
There is a little sheet metal trim cover on the left of the seat base. Holes for that are also already in the standard cab seat base.
It would be nice for Greg Hill to chime-in on this. Greg has Unison seats in his "regular" cab 1954 pickup, and Greg helped me deal with buying, fitting, and covering/upholstery my seats.
These are are rare, but they sure are "cool"/nice.