He's pretty close to the location pinpointed in RMS. He's in Morroc. If you warp to Morroc and go northwest along the edge of the crater in the middle, you should see him.
Make sure that you are *JOB* level 35 not base level 35.
You can use @whodrops itemnamehere and the game will give you top 5 monsters with the highest drop rate for the item. Tough Scalelike Stems is from Stem Worm. South of Aldebaran is the most convenient spot for them.