early a 5 speed converson

You'll need the OD. bellhousing with the OD since the OD bellhousing has the bigger opening to fit the OD. It's practically a bolt in.

I've done two conversions & seen 30 mpg on occassion in hilly N.E.

833 OD came in alum & cast iron versions in model years from 75 to 87 for various cars & trucks...Darts, Volare, Aspen, Dodge truck

Your best pick would be an alum version to keep down the weight.

You might have to make up a new driveshaft...my two 65 Darts with 904 originally did need new driveshafts when the 833 OD were installed.

Note the flywheel on early model slants have a smaller crankshaft hub provision than the 67 & up models so you must have a flywheel to fit your situation......adapting a 70's and later flywheel to a mid 60's slant won't work.