@robram
D3568100A.JCV and D3599100A.JCV are both split-screen 212*234 picture size, for nuvi 2xxx/3xxx and xx series respectively. Your 660 uses a 480*270 full screen jcv file, but it hasn't been posted if it is in fact available. You can probably use the 212*234 D3568100A file in your zumo, it may be washed-out looking and be 'stretched out' to fit in full screen because it can't display in split-screen.
It can't use the smaller D3599100A because that's made differently to most JCV files for US/EU firmware units, and it can only be used by 30/4x/5x [xx series] nuvis & SP Apps on phones.
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