J.R. mentions the mercenary group paying $300 per week as being quite an enticement for his friend to join. That's roughly four times what a man would earn if he joined the US army at that time. United states military pay for entry level personnel started at $374.40 per month in 1977.
In an earlier Barnaby Jones episode JR wanted to go undercover to infiltrate a Paramlltary group but Barnaby shot the idea down. Now JR gets his chance. Actor Mark Shera's experience working on the SWAT TV series helped him in this role.