3" is about right. To take a driveshaft apart, you have to unbend the 4 tabs on the metal collar, near the slip joint. Then, do what it takes to get them apart.
You may not have to take it apart. If the slip joint moves the 3" freely, why bother?
'79 CJ5, AMC 360, t-18/d20 twin stick, dana 30/amc20(Mosers), Edelbrock Performer intake, Holley 600, ps/pb, DUI HEI, 'glass tub/1pc. tilt nose, 33x12.50 BFG AT's.
There's a fine line between "hobby" and "mental illness".