the 3.9 is a 318 with 2 cyls cut off. a 318 will bolt up to a 3.9 tranny. IIRC the 3.9 is internally balanced, so the clutch/flywheel should work, too.

if using a manual, though, I'd use at least an NVG3500...I don't know if I'd trust an NVG1500 or aisin AX15 behind even a stock 318.

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)