This sign was made in both heavy porcelain and light metal embossed painted. My tin embossed version Has a "63" date on the lower left. I think that era is accurate for your sign as well. That style sign that was lettered "We Recommend Duco Dulux" was pre-1958. The version with "We Recommend Lucite Duco Dulux" was introduced in 1958. I believe the "Expert Body Repair" version came out a few years later in the early 60s.

http://www.oldgarage.com/photo-galleries/autopaint/

PXL_20210803_233750251.jpg
Tin embossed version


Jim "Oldgas" Potts
Your host and moderator