I forgot to add that there is a pdf manual for the 66-18 at http://ismacs.net/singer_sewing_mach...ine-manual.pdf which is more like your machine from 1947 and one from 1952 more like my machine at http://www.singerco.com/uploads/down...32979cb4e0.pdf

Janey - Neat people never make the exciting discoveries I do.

my 1949 crinkle 66 is what I use for a treadle. I just love coming into the quilt room and finding it waiting for me.
I hope you use and love yours!

I would guess that it's a 66-18. There are occasional errors in the ISMACS lists, due to misreading the original (handwritten) records, or typos, or errors in the original records. I suspect that someone just misread the -18 as -10 in this case.

It looks to be in very nice condition. I hope it works nicely for you! The 66's are beautiful machines.