Heard back from the member of another forum that regularly visits the BMHIT archives. From his information...
"With regard to left have drive PI TR6 there were 3600 assembled at the Malines factory in Belgium mainly for Holland, Belgium, France, Germany and Italy. Left hand drive PI TR6 were also assembled at Canley however I don't have exact figures. From the statistics that I do have circa 600 LHD were exported from Canley to countries such as Greece, Spain, Norway, Denmark, Switzerland, Yogoslavia, Congo, Tenerife and Iran so that would make some 4200 in total the bulk of these going to Switzerland. If it was assembled in Belgium it would have a commission number starting with either 1CP or 1CR.
I have a record of 1 x PI TR6 being exported to Equador and that is CP25789-L which is a Canley assembled TR6. It had engine no CP26008HE. Other TR6 PI exported to South America, I only have data for the years 1969 to 1972, include 16 to Guatemala, 1 to Mexico, 2 to Brazil, and 1 to SanSalvador."
I passed on the commision number listed on that info sheet. Will have to see what he comes back with.