[mikethedruid]

Just my two cents, you could also buy a single cell battery holder for an AA cell, and make any future changes simple. Once you rebuild the original electrolytic cans, and get rid of those big orange replacements under the chassis, there should be a whole lot more room. If you don't bother with re-stuffing the paper condensers, but just go with the yellow poly condensers as is, you'll have even more room. Should be able to find a place for an AA cell holder pretty easily.