Can I just cut off the wire tube on a mid year steering column and make it correct for a 15, or are there other differences?
The 1915 steering column was the same as 1914 at the beginning, and for most of the model year. The spark and gas levers continued to be used through the 1916 model year. After 1916 the spark and gas levers changed, as did the gear case.
Here is a January 1915 - August 1916 assembly for reference. The quadrant, spark and gas levers should be brass plated.
From what I understand for a short time when the quadrant was formed, the detentes were visible on the bottom. I had one some time back and if I only had known...
When in 1915? I believe this is the steering column introduced with the MAG horn. The encyclopedia says "beginning on some production in January 1915." The top one appears to have had water in it which froze and expanded it, but it shows the first type of electric horn button. The bottom one shows the type of tube used for the first electric horns.
Here's another view of the button.
Alright, thank you for the detailed answers! That was super helpful. It's one thing to read the index, but another to look at pictures of the differences!
The column in your bottom picture is typical of 1917 - 1918. That horn button was used from late 1915 until the combination horn / light switch appeared some time during 1918 model year production. The spark and gas levers shown were not used until 1917. It is identical to the column used in my 1917 runabout, one of the last cars produced that model year with serial number 202XXXX. Sorry I don't have a good picture showing details of the steering column inside the car. The spark and gas levers would have been nickel plated originally just on the upper end. They are bare steel under the hood as the steering shaft also was originally.
Kim Dobbins can probably share a picture of the column in the Rip Van Winkle '17 which would be the same.
The ends of the levers appear to be different. Other than brass plating for 1915, are there any other differences?
The steering gear box and the gear box cover have a slightly different shape for 1915 - 1916. The gear box design was revised at the beginning of 1917 model year and the material was steel, black finished (raven) at first. Then the material was revised back to bronze, with nickel plating as shown in your photo. This was still in early 1917 model year, about August 1916 in terms of the calendar.
See here for the note sent to dealers (AKA List of changes):
Looks like I have more parts shopping to do.
Here's a photo of a 1915 runabout - the engine number is 649458 with a December 11, 1914 casting date. A bit too early for even the experimental run of electric horns.
And just to be clear, the quadrant is brass-plated, not brass. Correct?
The quadrant is brass plated, stamped steel for 1915 - 16.