We know the Achilles was the 17 pdr version of the M10 Wolverine, but was its armament mounted sideways like on the Firefly?

No, it was not. It was a conventional, vertical sliding breechblock with horizontally opposed cylinders, basically the towed gun. I can't embed right now, but go to YouTube, look for my videos entitled "Inside the Chieftains Hatch Achilles". It's a two part tour of the vehicle.

I will give you three clarifications.

M10 was not called Wolverine. Nobody has a clue how it started, and we've been checking with some pretty solid authorities on the matter.

Achilles was the name given to all M10s regardless of gun, after Feb 1945. Similar to Sherman being applied to all variants of the M4 (To include Firefly, which was an unofficial name. It was officially the Sherman VC or Sherman IC.) So Achilles MkI or Achilles MkIC distinguished between the 3" and 17pr M10s.

Firefly's gun was not simply rotated 90 degrees, it was a significant redesign. They had to reshape the barrel, change the cradle, replace the hydraulic system, and convert the breech to slide horizontally while maintaining controls which were operated by a person standing upright.

Thanks for your insights.

When did the M36 start being called the Jackson?

I need some pics posted!

Officially, M36 started being called General Jackson in November 1944. There was a brief dalliance with Black Jack before they went with Jackson.

However, the troops in the field didn't really care what the Powers That Were thought the TD should be called, so the name really didn't take off. It hung around in institutional memory, so the name was always associated with it, but nobody was ever entirely sure why. By the 1990s, the theory was that a model manufacturer (M103 Longstreet?) or wargamer (our guess for Wolverine) came up with it, and thus it was pronounced to never have been named, because nobody could find any primary source proof of it. This changed about four years ago when I came across the naming order in the Archives which gave evidence for a number of pieces of equipment getting official names.



See my articles here,
http://worldoftanks.com/en/news/21/chieftains-hatch-whats-name/
and here for more info.
http://worldoftanks.com/en/news/pc-browser/21/chieftains-hatch-whats-name-pt2/

Here, a screenshot from one of my videos.



And videos.

https://m.youtube.com/watch?v=xmbWKayyLcI

https://m.youtube.com/watch?v=2waokK8VmnY

Quite the stout recoil system.  I like the travel lock on top of the recoil collar as well!

Very nice!!!