excessive cabin noise
 

Recent purchase of 57 convertable, D code, cruiseomatic, with 57k miles. Lasrt entry was Nebraska registration with 54K miles. So it hasn't been driven much. Have idle issues and engine misses at idle and at speed.
Experiencing significant interior "engine" noise. First thought was tappets, as that's what it sounds like inside, but standing outside vehicle, can't duplicate when revving engine up.
Open to suggestions on where to look. U joints?
Thanks
Bob