Is it just the shock or the brackets? The brackets are pretty generic. I had one on my old toyota that bolted to the idler arm on one side (the non-generic part, I guess) and the steering rod on the other.
Call an auto parts store that sells those and they should give you the part number. Rancho's web site is useless for that kind of information.
DO NOT use an RS5000 as your steering stabilizer unless you are using two of them. The shocks are valved at about 70/30 compression / extension. An RS4000 is valved 50/50 specifically for this application.