FYI update - I just received a pair of reman axle shafts for a '79 Horizon (purchased on eBay for $20 each). They should be the correct length, but the outer CV's may need to be changed.
Anyway, they were packed in a couple of dusty boxes, and protected with wadded up newspaper, from August 30, 1990. I guess these have been sitting on a shelf for the last 23 years.
Steve.