The leads are plain old bananas.
D Cell ni-cads are kind of hard to find. I got them
here but there may be a better price somewhere else. I think I convinced myself I couldn't use nickel metal hydride batteries.
One D size 5000 mAh NiCd Rechargeable Battery Flat top with TAB
Part#: CD-D5000TB
(Qty: 4 x $5.65)
Subtotal: $22.60
Tax: $0.00
S&H: $7.77
Final Total: $30.37