S-502/142B is the shelter of the AN/142B RADIO TELETYPEWRITER SET. It is a modified S-318/G shelter:
TM 11-5815-334-10
TM 11-5815-334-20
TM 11–5815–334–20P
TM 11-5815-334-20P-1
TM 11-5815-334-20P-2
TM 11-5815-334-34
TM 11-5811-334-34P 1977
TM 11-5815-334-34P-1
S - Shelter S-318/G