I believe the H-6 (straight vanilla Tu-16, assembled in China and specially modified for the mission) responsible for first nuclear test had the serial 4201:Now I'm confused, I thought the H-6A used in China's first nuclear test was aircraft numbered "50671" and the same one was used for the famous test no. 6.
The very first nuclear test AFAIR occurred on 14 May 1965, when a 25kT yield nuclear device (other sources say a yield of 35kT was achieved) was used during China’s second nuclear test at the Lop Nur (Lop Nor) nuclear test site in Malan/Xinjiang and in fact a military rated version of China’s first nuclear device known as "Project 596".
Or am i wrong? ... so they had two carrier aircraft for these test?
Note the heat resistant paint on the underbelly. Although this aircraft was modified for dropping nuclear bomb and the picture refer to it as H-6A it's not really a H-6A as that variant was approved on 15/05/1966, a year after the first nuclear bomb test.