Need Understanding of Interurban Car Dimensions

That would not have been my guess.  That is a drop platform car. The 43' 4"  is probably the length over the platform end sills, that is the overall length of the car.  The 33' 4" dimension is the length over the body end sills.  At the body end sill there is a step down about 10" onto the platform which is supported by the platform knees.  This would make the platforms 5' long. The truck and the wheels have to fit fully inboard of the body end sills so the truck centers are probably another 8' shorter than the 33' 4" dimension.  So the truck centers are probably about 25'.

This construction was common for trucks that used wheels 34" to 36" in diameter. By using a drop platforms, the passengers had one step down onto the platform and then had to use a single folding step to get down to the street.  This simplified car construction and speed loading.  To see what happens without a drop platform, look at the fully open cars which had two to three steps to get from the seats to the ground. 

The development of the high speed motor aliowed the use of 24, 26, and 28 inch wheels and got rid of the drop platform. This probably started about about 1915. 

Please post a photo of your finished model when it is done. 

David,

Thanks for your reply. The sketch below is my interpretation of your comments. Did I get it right?

Yes, except my guess was that the truck centers might be 8' shorter, so that would be four feet at each end.  But that is just a guess. Scaling that dimension off the photo will probably be required. And just like the real car, your trucks will have to fit under the carbody, so the truck centers might have to be adjusted. 

Thanks again David. I am anxious to get started building this car for my layout.