The information about which axles are involved probably won't be published in the "owner notification letter". Typically, that info is only in the "internal documents" such as repair instructions, reporting instructions, authorization certification, etc. From the information I have, the axles involved in the Jayco recall and in the Grand Design recall are the Dexter 44 axle line. That's the Dexter 4400 pound axle which is installed in "a lot" of xlite and ultralight trailers from all RV manufacturers.
You can find some of the information on the Jayco recall here:
https://static.nhtsa.gov/odi/rcl/201...8V618-5137.pdf