driveshaft length rear diff swap

Lonewolf3165 said
[Here is a chart with the different lengths of driveshafts & trans/ rear combinations.

What is the source for that table? It does not have (or I don't see) either of my combinations - 66 Barracuda 273/904/7.25 or 73 Duster 340/727/8.25

Are the measurement from the center of the u-joints on each end?