Pics of my oddball lockouts 67 K-20

[O'l Buck]

Here are the pics of the lockouts I've been having problems with, along with the spicer decal on the glovebox, and the option tag...does anyone know how to decode the options? maybe they might shed some light on this subject. I need to figure out what axle I have because the seal for the closed knuckle on the left is leaking and I'd like to replace it. Dad said anytime he ordered U-joints for it, he had to order 1 ton parts, but I was under the impression Chevrolet didn't make a 1 ton 4x4 in 67. I didn't scrape the grease off of it, but it has a 10 bolt cover and still has the differential tag, 4.55 gears in front. This truck is factory, nothing has been changed and to my knowlege, it hasn't been opened up since it was new, and Dad was the 2nd owner of it. It is factory equipped with Detroit lockers in both axles, and even has a decal behind the seat to explain that.

Anyone that knows anything about this animal, help would be appreciated.