Found the stamping for serial on my 1430. Looking for year and going by info from elsewhere, this is what I think I have then.
1430 - 2503-7702
1430 is model 2503 is actual serial? and 7702 is date, which means Feb. of 1977 then? That how it works. I was thinking of mid to late 70's or early 80's, so seems about right.