Hi wombat.  I don’t think the DDs have a drop box.  

It might be easier to just tell everyone you are going to find yourself a 10K powershift machine BP! You might like that one better. Regardless, good luck on your quest to convert it.
A photo of the “funky” shift pattern from a D7G, I think same as on some D6Ds. These seem to stump everyone trying to operate one without a diagram.
I thought the earlier 76As were only 5 speed? My memory is fuzzier than usual. JM

Hi JM.  I have considered finding a power shift d6c with junk undercarriage and swappping.  

yes changing your good track gear onto a powershift model is probably the easier task. probably easier to find a donor too.