Question on my Coronet RTs posi rear end

[17WithaCoronetRT]

I just bought a 1968 coronet rt was coded to come with a 3:23 suregrip posi rear end and has a large yellow "D" painted on it at about center, can you tell me what this means? any help would be appreciated, thank you.
Tyler

 

[Rolling Thunder]

"D" on the rear denotes year of rear I was told on a similar question I had asked. D = 1968

My 71's was marked with big painted GB which stood for 71 b body

 

[17WithaCoronetRT]

Thank you so much! we were thinking the yellow paint meant junkyard!