In the mid 60's, while in the Marine Corps, the term splib was used commonly among black and white marines. It was not used in a pejorative way by either blacks or whites but as a "hip", descriptive way of identifying a person, usually a male, of the negro race, such as in the phrase "splib dude". Likewise the descriptive and non-pejorative term "chuck" was used to describe a white person, however it was also used to describe the Viet Cong (VC), such as in "Victor Charlie", "Charlie" or just "Chuck" In fact, one might get vanilla or chocolate creme filled cookies that were included in the field "C" rations. These were commonly referred to as "chuck" or "splib" cookies.
At North Texas State University, 1964, splib was the common word for black African Americans used by the jazz crowd. Gray, or gray dude, referred to whites on a similar level. These were in common usage among many civil rights activists as well.
I did not perceive it as derogatory at the time, more a hip code-word among the jivers (those speaking jive-talk).
That splib band had a lot of soul; the gray dude couldn't keep up.
When I was a military brat in Germany in the 60s, splib was the accepted use for blacks, it was not derogatory at all. On the other side of the coin, 'chuck' indeed was the term for whites, and you even heard 'chuck white' to describe someone who was white.
To describe a group of blacks you would simply say they were all splibs.
This is definitely not a derogatory reference to blacks. With the 3rdMarDiv on Okinawa in the 60s, it was used back and forth between blacks as well as between blacks and whites. If it were derogatory, I would have gotten my ass whupped many times. Beyond Okinawa, in VN and later in Yokosuka, the term was prevalent and used in a non-pejorative manner. The term splib was used to identify blacks or African Americans in a non-insulting way.
Where are the splib bars? The splibs hang out in the "Hole".