727 Tail shaft
There are two different tail housings that are the most popular, one with a slip yoke ("long" housing) and one this a bolt on yoke ("short" housing) The "long" housing was use in trucks/vans that were short enough in wheelbase that a one piece driveline could be used and also cars. The "short" housing was used on long wheelbase trucks with multi-piece drivelines.
There are other housings available for industrial/motorhome chassis applications that had "E" brake mounts for a drum brake, but you don't see them very much.
All "long" housings are the same length. As stated earlier, there is a "long" heavy-duty housing but it is the same length as the standard duty.
Chuck