About the lid,
I don't really know. Mine was made in June 1964 and the underside of the lid was "untreated". Whenever I see pictures of these new one's, never used, 1983 models, both sides of the lid are painted. That's all it is. Painted or unpainted aluminum. When I restored my 64, I painted both sides after sanding it down. It still looks new. Just did 4 loads in it this evening.