Analysis of information sources in references of the Wikipedia article "Patrol Boat, River" in English language version.
The 11 PBRs delivered in March 1966 and the approximately 300 delivered over the next few years to the U.S. and South Vietnamese military...In 1967 the Mark II version of the PBR appeared, with an aluminum gunwale to protect its sides when junks and sampans came alongside. A transom lengthened the boat by about 6 inches. Most of the 418 Mark II PBRs constructed by Uniflite
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