If you go to Luftwaffe Archive or link below and go to the misc area and then drop tanks is shows a drop tank simular to the one you have posted here. Unfortuently its in german so not really sure what it says about it.
Using altavista as a translater this is what it said for the picture.
By the frequent transfer of combat forces - "flying fire-brigade" - the problem of the transport of the necessary ground support equipment always became, since the existing transport aircrafts were needed urgently for the supply supply of the front. The construction DOBBAS lay the demand to reason to use normal combat aircraft for the transport of bulky loads to be able. The test site Rechlin developed and tested therefore the transportation equipment DOBBAS in the year 1942 with the airplane samples He 111, Ju 88, Ju 87 and ME 110. For the transportation equipment DOBBAS were the following devices for transport with a max. Load intended by 1061 kg: Pak 3.7 cm, Pak 5 cm, air landing cannon, mountain cannon, flakgeschuetz 2 cm or Krad with sidecar.
There were cargo versions of the B-17 and B-24 also. They didn't carry additional pods, that I know of. It is one way to get more work out of your war weary bombers or get stuff moved when nothing else is available.