are these original

Clean 'em up and take a picture of the markings. Most shoes and pads will have codes stamped into the metal and 'edge codes' inked or stamped into the edges of the lining. That will help figure out if they were original. Because of the rapid changes in shoes even without a number, a picture has good potential as a clue.
FWIW
10x1.75" rear shoes through Feb '67 are FMSI # 256. March '67 through the end of '68 model year they were 288. For model year '69 they switched to 331 along with the new style adjuster system.

The Chrysler Master Technician's booklet 69-7 recommends the "new grooved" linings. See page 5. (booklet online at www.imperialclub.org as well as hamtramck-historical website).