Thanks,
I think a LASCO S-424-2 might work as a substitute for the cold side. I’m wondering whether the outer metal piece with pin screws off. There appears to be an o-ring between it and the 2nd metal piece. I assume the o-ring is part of the inner cartridge.
Ordered the cartridges. Cartridge came out easily with the knob handle on and pin removed. The new seat didn't fit so replaced the o-ring on the old. Difficult "for me" to get the new stem in and properly aligned but it solved the problem. I think I'll wait to replace the hot water cartridge. If it ain't broke don't fix it. Thanks for your help. Total cost , $6.99.