Just wanted to post this for the two or three other folks in the whole world that may be using a ZD back The Mamiya PB 401 batteries are outrageously priced, ($169.95 at B&H as of this writing) and precious little information is available about optional replacements or substitutes. HOWEVER, after a little digging, I found that the Minolta NP-400 is a direct replacement and as of this writing is available from B&H for $9.95 -- yes, that's $9.95. FWIW...
Cheers,
Cheers,