Mike's Penrite Steering Lube is NGLI 00 grade, which is the proper stuff to use.
Member drdoug has sold Chevron NGLI 00 gear oil on here. I don't know if he has more, but a PM to him could find out.
With the proper grade, there's no need to try to custom mix chassis grease and gear oil, although that would work as well.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.