If it measures 48" with the yoke pushed all the way in the transmission, then you need it shorter. If they pushed the yoke all the way in, then pulled it out 1" (or maybe 1 1/2") and came up with 48", then 48 is it. Like someone else mentioned, if the DS is too long by an inch or less, you could move your axle back. That will give you the room you need for the drive shaft, and bigger tires if you ever plan on running some big slicks.