Sweden's railways are so well electrified that diesel traction does not play much of a role today. Green cargo uses diesel shunters (typically class T44 or Td) of course, but other than that the state railways SJ and its cargo part Green cargo only have some small diesel tractors or locomotors and typically they are also quite old. Private operators have bought used SJ/GC diesel machines, especially those of the types T43. This title picture shows a class T44 machine in Mora 23.8.2009. The T44s have become fairly rare recently because Green cargo is putting them one by one through a thorough modernisation programme, after which they are designated class Td. Photo by Ilkka Siissalo 23.8.2009 in Mora.
Please note that there are pictures of diesel machines also in the category "Private operators' locomotives" and many of them are even still in SJ's or GC's colours as private companies have bought them but haven't bothered to repaint them.

Here you can see clearly one of the key reasons why Green cargo wants to modernise and revamp the T44 diesels.
A T44 shunting at the Borlänge central station 23.8.2009. Picture by Ilkka Siissalo.

T44 394 switching at Stockholm Central Station, December 1996. There is otherwise nothing special in this old picture, but note the SJ logo at the front of the machine. The picture is from those times when SJ was still SJ and such a thing as Green cargo did not yet exist. Photo by Urban Fredriksson. Uploaded Jun 18, 1997

It's rare to see a T44 still in the orange old colours of SJ of the 1970s, but here was still one in Kiruna 14.8.2009. Picture by Ilkka Siissalo.

One of the very first class Td diesels of Green cargo. It is an old T44, but thoroughly modernised and rebuilt and thereafter called Td instead of T44.
Photo in Nässjö 29.6.2010 by Ilkka Siissalo.

A smaller diesel of the class V5, still in the very old SJ orange colours 23.8.2009 in Enköping. These three axle locomotives were built 1975-78, altogether 40 pieces. They have Deutz diesel engines and their top speed is 40 km/h in shunting mode or 70 km/h in line operations mode. Picture by Ilkka Siissalo.

Another view of the same V5. Picture from Enköping 23.8.2009 by Ilkka Siissalo.

Another V5, this time in Alvesta. Picture 30.6.2010 by Ilkka Siissalo.

T43 235 at the Swedish Railways' Museum at Gävle, March 1997. Photo by Urban Fredriksson. Uploaded Jun 18 1997. SJ and GC have not had the old 1950s class T43 Nohabs in use for a long time anymore, but still today some of them are in operation by private companies.

One of the former class T43 diesels of SJ, moved from SJ to Banverket, the infrastructure part, here in a sorry state forgotten on a side track in Vetlanda. It was a playing ground for vandals and little boys. Picture in Vetlanda 30.6.2010 by Ilkka Siissalo.

This also once was an SJ class T43 diesel.
Picture in Vetlanda 30.6.2010 by Ilkka Siissalo.

Class Tb diesel locomotives are quite special as they are used not only as regular locomotives in track maintenance trains but also as snow ploughs. This is a Baneverket class Tb in Kiruna 14.8.2009. Baneverket is the former infrastructure part of SJ, now operating separately from the train operator part SJ itself. Picture by Ilkka Siissalo.

A class T21 diesel at a railway museum in Nässjö. SJ bought 54 of them 1955-58. In 2003 only three were left. They were built by MaK in Germany and the same type was in use at least in Germany, Denmark and the Netherlands. Picture at the Nässjö Järnvägsmuseum close to the Nässjö station 29.6.2010 by Ilkka Siissalo.

The light shunter Z70 is officially classified as a locomotor. Picture of this Green cargo Z70 in the very old SJ orange colours is from Gällivare 13.8.2009. Picture by Ilkka Siissalo.

Another view of the Z70 from Gällivare 13.8.2009. Picture by Ilkka Siissalo.

A class Z43 locomotor of SJ together with an old express train coach of SJ at a railway museum in Nässjö. Ten of these were built for SJ in 1954. Photo 29.6.2010 by Ilkka Siissalo.

Side view of the same Z43 as above. Photo in Nässjö 29.6.2010 by Ilkka Siissalo.