The FKP-58 pod included a camera and a VM-505B "Saturn" videorecorder.
It was used to record on video tape the firing sequence of a missile. 
This pod was observed on several MiG-27K 
(> <a href="http://www.16va.be/page_mig-27_fkp-58.html"><strong>LINK</strong></a>), including some carrying a 
Kh-29T TV-guided missile.
The pod photographed here was lying on its back.