Just dropped a late 1971 slant six in an early 1965 Valiant , auto trans. Buttoning up details...with engine idling. trans in neutral, reverse or park with brake on all Ok and smooth. Problem: trans in drive, very slight throttle I get a deep rumble rumble felt in the steering column and entire sheetmetal/body.. I know its hard to diagnose noise's, but any suggestions all clues ?. My other car '65 dart quiet , no rumble under same circumstances.

Is the exhaust pipe touching the floor, steering linkage or cross member when engine torque is applied?
DD

This reminds me of EVERY girlfriend I've ever given a ride to in any of my 60 some odd mopars thru my life. She say's "whats that noise?".....You respond by saying,"what noise?".

HAHAHA so true

I think Eric hit the nail on the head in his response at .com. Unless you had a special torque converter made or used the adapter ring, the small snout of the early tranny torque converter is likely 'rattling' around in the larger crank pocket of the later slant.

-S/6