First off I have never seen a d70 in a 3/4 ton gmc.
I've only found two 3/4 tons with the D70 in it, one was a '69 Chevrolet Camper Special my Grandpa bought new, the other was a '72 GMC Camper Custom I looked at buying from my Uncle. Could possibly have been an odd option, certainly rare for sure.
On the Locker, I could have sworn that I saw that listed for the Danas in GM trucks, perhaps it was in a different brand (Ford maybe?).
