electech, after doing some more research I found RJ45 and RJ48 are the same plug, just wired slightly different.
RJ (Registered Jack) designations are a specification for a particular jack/plug, wired to a specific USOC wiring pattern as originally defined in fcc part 68.502, and now defined by some independant industry board that I can't remember the name of, nor can I find the newer designations.
A jack/plug does not gain an RJ designation until it is wired, although there are specific jacks designed for specific applications that could be specified by a RJ designation.. examples might be RJ-31x and RJ-38x jacks which have shorting bars for alarm supervision.
The 8 position modular jack/plug is used for a number of different USOC applications, with differing RJ designations. Ethernet, token ring, etc do not have RJ designations at all.
RJ-61, RJ-41, RJ-45, RJ-48, RJ-31, RJ-38, ethernet, and token ring all use a 8 position modular jack/plug, with different wiring patterns.