On May 19 and July 12, 1966, respectively, three black Orions (148669, 149673 and 149678) were handed over to the Republic of China Air Force (RoCAF) (today known as Taiwan).  The RoCAF flew them for a very short period in support of a covert CIA program. All CIA P-3 missions were called off as of January 25, 1967.

After all three were returned, two were converted to EP-3B (149669 – PR32 and 149678 – PR-31). As indicated in one of the related posts, the two EP-3B arrived in Japan in 1969, providing much needed relief to the overworked Willies (EC-121M).

The third buno (149673) was converted for another (non-SIGINT) special mission. Both of the EP-3Bs flew extensively for the remainder of the Vietnam War and long afterwards. Sometime in the early 1980s PR-31 went over 20,000 flight hours, making it one of the high time P-3s in the Navy (if not the highest), followed shortly thereafter by PR-32. Both continued to fly until the late 80s when they were retired and replaced by newer converted P-3s. So the PR-32 that landed in Hainan was not the original PR-32, but the replacement. The two Bravo birds (aka Batrack) had unique backends, different from the EP-3E ARIES later flown by VQ-1 and VQ-2.

Source: From Bats to Rangers (FAIRECONRON TWO)