As I've explained a couple of times, the Achilles turret is externally the same as the late M10. Same shape, same counterweights. The differences were the 17 pdr gun, revised internal stowage (the 17 pdr's rounds were larger than the 3 inch gun's), and a slightly modified mantlet. See the photo below of a standard late M10 turret. The late turret was chosen for the Achilles conversion because it was better balanced and roomier than the early M10 turret.
Also below is a late model M36 with the double baffle muzzle brake. Note that there is no fume extractor. By this time, the bolts on the side had disappeared.