Originally there was no number on the driveline only paint markings to help the assembly line workers put the correct one in the right car. For replacement purposes Ford assigned a part number associated with each driveline but cross referencing the number to the driveline is not easy as there are thousands made through the years.
Because of this your left with taking the details of the one you have and comparing them to what was originally installed
Some things to check
Is it a solid (one tube) from end to end or is it one tube inside of another?
Is it a straight tube or is it tapered at either end?
How long is it, what are the dimensions of the yokes at both ends (not always the same)?
Is there any markings left on the driveline?
Each of these can help lead you to a possible conclusion - was this a driveline that would have been in my car originally
We can see what the replacement part specifications were - they might be the same as original or may be a replacement so that one size fit more, to reduce inventory for Ford