Despite its rapid development, after testing late in 1941, and some airframe strengthening, the He.111Z proved to be an efficient glider tug, with more than enough power to tow the new giant gliders. The He.111Z entered production early in 1942 and were placed in service that year. Only the prototypes and the first few production models used He.111H-6 airframes; the remainder were based on the He.111H-16. They were very successful, and well-liked by the crews.

Bizarre plane 2

Another view of the Condor Legion reviewing before Hitler. June 6, 1939. (scanned by HOS Bandit)

Condor Legion 

Not a good quality photo but it allows us to better understand this singular project. 