Javeline thrower Devinder Singh added another gold as the Indians also won four silver and one bronze at the Chanthaburi Province Stadium.
With today's gold, both Inderjeet and Johnson completed their golden hat-trick as they had bagged the yellow metal in their respective events in the first and second legs of the series held in Bangkok (June 22) and Pathumthani (June 25).
Johnson led men's 800m final all through with a timing of 1:50.56 while Inderjeet produced a best effort of 19.83m to take the top honours. Devinder justified his selection with a gold-medal winning throw of 76.61m in men's javeline.
Arokia Rajiv and M R Poovamma bagged a silver each in men's and women's 400m race, clocking 46.07secs and 52.60secs respectively, while Gayathri Govindraj also clinched a silver medal in the women's 100m hurdles, clocking 13.76secs.
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The women's 4x100m relay team bagged a bronze with a timing of 45.42secs while their men counterpart finished fourth, clocking 39.83secs.
In other events, triple jumper Sheena N V finished fifth with an effort of 12.96m while 2014 IAAF World Junior Championships bronze winner in discus, Navjeet Kaur Dhillon produced her season's best throw of 53.53m to finish fourth.
The gold medallist of an individual event gets USD 1500 while the silver and bronze winners pocket USD 800 and USD 500 respectively.
According to organisers, all the athletes are required to participate in all three legs to be eligible for the prize money. There is no prize money for relay events.