Here are copies of the covers for the 1951 HJ and 1953 Kaiser Manhattan models Banthrico offered. I checked with the company back in 1976 & the casting dies for the two vehicles were already scrapped out & it would cost between $6,000-$10,000 for them to re-measure and re-tool off an existing vehicle at that time.
As noted in the page on the HJ, colors Banthrico offered were Mariner Gray, Ceramic Green, Blue Satin & Cardinao Red (so you can tell if the one you come across is a repaint). Also, if you look carefully, you will find there is a decal with dealer information on the roof of the car at lower left on the page. This is what they mean by Imprinting as noted. I have yet to ever see (let alone own) a Spring Motor Powered Model version of the HJ. Both the coaster version (no spring motor) and the spring motor version have Tenite plastic bodies, same material that the Kaiser Deluxe/Manhattans of 1951-54 Early Special types were made from (around the metal center armature).
The 1953's were a different story. They were offered to dealers in 18 car cases for $28.50 FOB Chicago IL. Each case included 1 1953 Kaiser Manhattan in 12 single colors used on the big cars & 1 each of 6 factory two-tones (color combinations offered for the big cars as well as break points for the colors). Otherwise, the standard assortment was 12 cars minimum (Banthrico choice of colors) at $1.53 each. If a dealer ordered at least 100 cars, the dealer imprint would be free; otherwise the minimum set-up charge of $8.25 for dealer names (1 to 99 cars) applied. Keys to open the banks went with each car. Dealers in Illinois ordering 1953 models were required to add 2% to the order cost, dealers in Indiana had to add 3%. Shipping was based on F.O.B. Banthrico's Chicago IL plant.