Phil, I have these dimensions written down as being:
36-3528 - 0.640"x 1.25"x 0.125" (1/8" thick as Ron said above)
66-5524 - 0.640 x 0.950" x 0.078" for the one inside the speedo drive.
This came from a discussion on the forum years ago - at the time there was discussion around the quantity of the 1/8" spacers as I think it was Russells who listed one while other parts lists show two.