http://www.moparts.org/Tech/Archive/axle/5.html

about 11/16"....I didn't have a problem using a driveshaft from an 8.25" M body when I put an 8.75" in my 5th ave, still had ~ 3/4" of play in my slip yoke.

1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)