The number 805  never appears on the trail car. That  was  the IVES catalog number for  the 809 and 810 trolley trail cars. These trail cars were only sold separately and are much harder to find than the powered trolleys. The first catalog to list either of these trail cars was 1912, but they listed in the 1911 price list.

 Above and below are two early No. 810 (805) trail cars, they are identical except for the roofs. The No. 805 trailer was always listed in the catalog right below the No. 809 Trolley. Basically No. 809 was the number Ives used for the track powered trolleys and 810 was the number used for the overhead pole trolleys. Unfortunately IVES used whatever bodies they had and No. 810s can be found with track power, although I've never seen a legitimate No. 809 with an overhead pole.

Look closely at the frame above and the bottom view below. IVES actually took a frame from a No. 50 series car and inserted it into the bottom of the trolley shell. This was necessary because the trolley frame was not originally designed to hold a functional axle. The 50 style frame on this trailer is gray indicating early production.

The above picture shows an 809 trailer. The picture below shows the same trolley from the bottom up. Note that this example also uses a No. 50 series car frame, but this one is black denoting later production. 

Here's a late trailer with plain frame. The frame insert on this trolley used to support the tin wheels was not made until 1915.