Fret--as I remember the spindle bearing sizes were the same sizes for the front and was simple (I think)to change the car front breaks to the truck and the rear pivoted just as the truck pivots on the spring hangers, so was probably simple to insert the rear end and get the better gear ratio of the car rear end also.
I have been wrong on things my memory tells me (senior moments)or CRS syndrome, but with 5 lugs front and rear that would have been the cheap way to go, not seen it done but should be possible, maybe not as simple as that but back then there was not much choice/difference in cars and trucks ( 1/2 tons in anything other than sheet metal and bed space)
