Hi Bill,
I use silicon spray on these old rubber parts.
The real challenge with this NOS shifter boot is the installation. Since the rubber lost some of its elasticity, it is almost impossible to stretch the neck wide enough to fit around the reverse detent of the shifter. I tried soaking the rubber boot in warm soapy water, no chance.
Finally, I made a small cut in the neck of the boot and glued it back after installation.
Laurent