I bought some Buna-N (oil resistant rubber) round stock, 1-3/8" OD x 1/2" ID x 6" long from McMaster-Carr and made the new seal in the lathe.
Boring the ID
Cutting the OD
Smeared with liquid soap, pressed in with a socket
For future records:
This shock has various markings:
ALCC14 which means for Light Commercial and High Powered Pleasure Cars
and on the brass disc 92-10 X
The one from the other side appears to be identical but newer, less rusty anyway, possibly a replacement from 6 or 7 decades ago, and has these markings:
and on the brass disc 92-10 Y
There is cast in number Y9014/8A on the back, a logo SDF and a patent no. 360168, which turns out to be for the rubber shaft seal and the rubber in the links.