i am not looking for time period correct i just want a good replacement i looked at a shimano alivio rd itm410 it says 7/8 i figuire that means 7or8 speed on the bad boy there's a hanger attached to the frame i think the alivio is direct mount does this matter this is new to me i've got the mechanical skills but the formulas, chain wrap , and all i'm still trying to learn it seems its a hanger from the frame to the shifter can i remove it and attach it to the new derail