A lot of people have used WFC Soundwave but I didn't think the proportions were right for Ironhide. The Onslaught/Impactor mold seemed more appropriate to me, so here it is.
This was an Impactor with the combiner plugs removed.
The forearms are from a deluxe armada Optimus. I used Impactors elbow joints, and let me tell you they were a pain to get out. They were blind-headed ie you can see only one end of the pin. So I had to heat it up, prise it out of the arms, then heat it up again to get the pin out of the joint and thread it through the new forearms.
The head is from classics Astrotrain. I had to widen the collar a bit to give room for the head to swing down.











I like to imagine his arms are fuel tanks or booster pods.