The spring 1955 Sears catalog shows what is unmistakably the all-metal body with a price of $69.50, marked down from $74.50 The stock number is 28KM6199F. This catalog marks the first appearance I can find of the steel-box single-wheel Allstate trailer popularly known as the “Tag-along” trailer (although I could find no indication that Sears ever called it by that name). Since the retail price is only slightly below that of the 1956 catalog, the date ascribed to the circular seems reasonable. It seems to have shared the same wheel assembly with the other trailer, but has a different tongue arrangement, with the new tongues being longer and designed to fit only underneath the bumper. Its load capacity was also 500#.This all-metal trailer appears identical to one sold in the 1950s by Dunbar Kapple, a trailer manufacturer in Geneva, Illinois, about thirty miles west of Chicago. (Dunbar Kapple was said to be partially owned by Sears.) The model number of the Allstate trailer was 231-963. Under Sears’s numbering system, the first three digits indicated the manufacturer, and it happens that this prefix was also used for Sears two-wheel trailers sold under the David Bradley marque (David Bradley was the Sears marque for the agricultural equipment they sold.) So the evidence suggests that Dunbar Kapple made the single-wheel trailer as well. The next Sears catalog I could locate was the Spring 1956 catalog. In this issue, the “station wagon” version has been dropped, but the original version, with the blue-painted wood cargo box, has been retained and now sells for $69.95. The all-metal trailer now sold for $77.50. If you had a 1955 Chevrolet, there was a version specifically for that model, but it isn’t stated what the differences were. I would presume it used a variant of the bumper mounting hardware. The Spring 1957 catalog shows the same two trailers, with the inevitable prices increases to $76.50 and $89.50. Again, Chevrolet owners are asked to note that on the order forms, so they can receive the proper trailer hitch configuration. The Fall 1957 catalog shows the same trailers, with separate model numbers for the versions that are used with 1956 and 1957 Chevrolets. In the 1960 catalog, the all-metal streamlined trailer is gone. Only the original version remains in the catalog, with a price of $77.00. Since the cargo box is described only as “dark blue,” it’s not clear whether this a wood or metal body. Although the trailer is still described as being made in Chicago, both the stock number and the shipping weight are different. Model numbers for streamlined metal 231-963 (“1956 or 1957”) 231-96369 (found in Canada). (Written and research provided by John LaTorre – A Short History of Allstate Single-Wheel Trailers)