Wes,
I bought it off of Ebay about 8 years ago and it was listed as an unused gear set for a D70HD. That is what I was planning to put it in, but I wound up buying a new axle for my dually instead. It appears to have never been installed or used. The numbers on the ring gear are:
12 7 89 SPICER T34842MAIAD429 41-9
Pinion:
SPICER T 40958 41-9 MAIAD305 1
Both serial numbers are 6649
You may be able to tell from that if it is actually for a 70HD or not, I have no way of knowing for sure, other than that is what it was listed as when I bought it.