Are you serious?
You have no idea how that junkyard axleshaft has been treated
The boots could be older than yours
The joints could be worn
If your axleshaft wasn’t making noise, I’d just throw 2 boots at it. If you want to be a real cheapskate, I once got $5 boot kits at Pep Boys. A few years later, they were still quiet and holding up well
And NO trip to the junkyard required
The devil you know . . .