I decided to change the gears in my 91 ZR-1 from 4.56 to 3.73's for better streetability. During the swap I found some very inexpensive Spicer u-joints for the driveshaft and halfshafts. Spicer 5-785 & 5-799's.The entire set was $86.00 shipped.
After they arrived I noticed none of the caps have any coating to prevent the steel to aluminum galvanic corrosion even though I specified they were for a vette.
After reading all the woes of obtaining the correctly treated u-joints I decided to see if there was a way to effectively treat the caps that would be in contact with the aluminum yokes.
(note: for corrosion to happen the 2 metals also have to have a liquid dielectric for molecular migration) In the rare event someone would wash their u-joints with a pressure washer or even worse, drive in the rain, I can't see moisture getting into the parts. Corrosion would be minimal or non existant if the parts were kept dry.

At any rate , my solution was to coat the caps with something that could remain intact during assembly and isolate the steel from the aluminum.
I found "self etching primer" by Duplicolor to do the trick.
I used an old cap, free of any coating, cleaned it with solvent/degreaser and prepped it with #400 wet or dry sandpaper.
After 2 light coats of the primer and about an hours worth of air dry time, I pressed it through the bore in the aluminum yoke. Not just once but twice.
The primer is still intact.

Yes, it takes a little time to make sure the cap is clean befor priming and a little patience goes a long way to be careful and keep the cap straight during assembly. But $5.00 for a can of primer can do a lot of u-joints. Make sure you return the cap to its original position on the u-joint as per Spicers recommendation.
If anyone is aware if an issue with this method please let me know befor I get it all back together.

 

After assembly, you could check for electrical continuity between the yoke and the end of the u-joint cap, with a digital multimeter.