Hi Ron,
You may be in luck here, as the 6V 40AH and 12V 22AH used a rubber strap rather than pair of metal handles, and this is fixed by a plate with four holes.
(I have seen a metal-cased example (bare shell) with a stamped steel handle in place of the strap, but that didn't look to be easy to use, and would rattle when carried (unless padded), as it rested against the side of the case.)
WFTW Volume 2 has drawings showing batteries, but some of them are the 6V 75AH and definitely not man portable!
(I'm still looking for some 12V 14AH ones to go with the pedal generator - so far I've only seen stripped cases without the rubber 2-pin sockets only used on those batteries.)
I'd like a complete (even if dead) one for the hoard.
There are also two variants of the backpack carrier: original with straps that go all the way around the pack to hold the flap shut, and a modified version where the free (Tag) end has been sliced off the shoulder strap and stitched to the flap instead.
Best regards,
Chris.