I got an HO52 with No-Spin under my 70 Suburban. I believe it's 4:10 since it's an auto truck, but could be 4:56 since there is nothing on the SPID other than No-Spin. If you want the whole axle I would need to find something to replace it with though. It also has a skid plate over the center section, not sure if it is Home made or factory, but it is bolt on.
Let me know and make me an offer. You'd have to pick it up, and if you are in a hurry, you'd need to come help remove/replace it since I am not planning to remove the axles til most of the rest of the truck is parted. truck is in 13901.