Something that I see quite often on various forums and the like, is misidentification of the early EMD 567 series engines. Like all engine manufactures of the day, the EMD 567 line was under constant revision throughout the years. This is not meant to be any sort of history of the engine, just a simple way to differentiate the different types of 567 engines.
The “Straight” 567

The first production model of the 567 was just that, the 567. Often people dont associate this engine, thinking the 567A was the original, but it was not. The first 567 engines used an interesting top deck design, with extended crab studs to hold down the covers, with a simple rectangular hatch over each injector. The first pair of production 567’s according to the EMD book “Diesel War Power”, were for the Moran Towing “Thomas E. Moran”, built by Defoe Shipbuilding in 1938. Ironically, an engine designed specifically for locomotives, would be first installed in a tug. The engines (one pictured above) were V8, 660HP/750 RPM engines that drove a 400kW generator, with a 24kW belt drive exciter above.

The first Railroad use of the 567 would follow in October of 1938, with a set of E4 Streamliners for the Seaboard Air Line railroad. Each E4 used a pair of 1000HP 12-567’s. The first and most obvious way to spot the straight 567, is the very wide housing for the blower drive gears, making the rear end of the engine rather wide. EMC/Cleveland would supply special versions of this engine to the USCG for use in a fleet of Icebreaking Tugs, with a narrowed version of this case, however all of the standard production engines used this wide case. By now, the engine also featured matching doors on both the crankcase and airbox, as well as a larger, removable cover that spanned the entire top deck.
Note the upper deck of the engine in the “U” (cast) or “V” (fabricated) upper portion where the exhaust coming out of the heads would mate up with the upper manifolds. The original EMC 567 design is well outlined in Eugene Kettering’s paper on the History and Development of the 567, which will be linked to at the end of this article.

567A
With the onset of WWII, the 567 by now was being refined into the 567A starting around 1942. What would put the 567 line on the map, would be the advent of the Navy LST program. The majority of the LST program would in turn use a pair of 12-567A engines (dubbed ATLP/ATLS for Aux. Tank Landing Port or Starboard), driving a 2.48:1 reduction gear through an air clutch. On land the 567A was being used in all of EMD’s line of locomotives from switchers to road power.
The 567A would take the idea of the narrowed blower drive on the USCG 8-567’s, and make it even narrower, thus saving crucial space in the engine room. Midway through the LST program in 1943, the two piece floating piston and carrier design was adopted. Also to note, is the entire upper deck was modified, and now the exhaust from the heads ran inside of a water deck. Note the smooth cast ducts for the scavenging air from the blowers into the airbox.

The 567A package used in the LST would go on to be one of the most common repower package for tugboats in the 1950’s and 60’s, something we will get into more in the future.
567B
The 567B was introduced after the end of WWII. The 567B was very similar to the 567A, with one main spotting difference on the outside. The 567B now used a ribbed air duct casting from the blowers into the airbox.

Mechanically the 567B was essentially the same as the 567A, with the difference being the attached oil strainer housing on the front end of the engine.
567C
In 1953, EMD introduced the 567C. The C block engine was essentially an all new engine. The C blocks major change involved the elimination of the water deck liners, and the use of O rings to seal them. These O rings were prone to fail, and would thus cause water contamination of the lube oil system. The C liners used a bolted on water inlet type, completely eliminating the water deck.

The easiest way to spot a 567C – is that the block introduced a few new changes. First is the round inspection covers on both the airbox and crankcase. The fuel rails were moved to the inside of the upper deck, as well as an all new style of hinged upper deck cover, with snap latches. The thing about the 567C is that it is also identical to its replacement, the 645 series.
567CR
A short one here – the 567CR was only an 8 cylinder engine, that used a revised firing order, hence the “R”, to help with vibration issues. Externally it is exactly the same.
567D
The final installment in the 567 lifespan development is the 567D of 1959. The D line of engines introduced the turbocharger. EMD, unlike Detroit and Cleveland would develop their own turbo, that was driven off of the gear train through a clutch at low speeds, and would freewheel when the exhaust pressure built up. The 567D was only offered as a 16 cylinder engine, and topped out at 2500HP. Later on they would take the turbo off for a few select applications, and squeezed 1800HP out of it. The 567D2 (used in the GP20 locomotive) utilized a slightly different turbo design, with straighter appearing ducts into the airbox.

The turbo versions of the 567D while overall successful engines and were a major stepping stone to the 645 development, they were plagued with turbo issues. Several railroads choose to pull the turbos off and replace them with the traditional roots blowers.
567AC and 567BC
The AC and BC engines, from the outside are identical to their original counterpart. Internally, the engines were upgraded to use “C” block liners. The only way to spot one of these, would be to remove an airbox cover and see if the water manifold is present.
567CA
Not to be confused with the above conversions, the 567CA engine is its own beast. While it was not any sort of a new development, the CA engine was an EMD designed direct replacement for the 567ATL LST engines that by now were in hundreds of commercial boats.

The CA engine used a new crankcase with “C” specs (including liners as well as cylinder heads), however there were several recycled parts off of the original ATL engines. The smooth blower ducts, as well as the entire top deck assembly, complete with the external fuel lines and removable covers were recycled off the original engines.

645C
Yes – the 645C is actually a 567. The 645C is a 567C that uses 645 power assembly’s. Again, like the AC and BC conversions, the 645C is not distinguishable from the outside.
Wrap up…
Please note, I wrote this simple as a way to try and help to visually distinguish each model of 567. One thing to keep in mind, is the 567 was a very modular engine at the end of the day, and quite a few components are interchangeable throughout the entire production line, some easier then others.
As mentioned previously, the 567 was an EMC/EMD design, and was built in the LaGrange shop. Between 1938 and 1961, both marine and stationary versions of of the 567’s were marketed and sold under the Cleveland Diesel banner, having been converted for such uses in their Cleveland shops. These engines carry Cleveland Diesel builders plates, and numbers.
Preston Cook, one of the leading authority on EMD, has a fantastic write up at the following link which gets a bit more into the technical sides of the model development over the production spans.
Preston Cook – EMD 567 in the 21st Century Eugene Kettering’s paper “History and Development of the 567 Series General Motors Locomotive Engine” hosted over at Utah Rails.