How many 1986.5 Porsche 928 5 speeds were built total and how many went to USA?

The 1986.5 model was produced solely for the US and brought the 1986 model up to the 'rest of world' 1986S specs.

First find the total number of 1986.5 models produced and the gearbox code using the VIN Decoder: From the OC site home page select..... 'The Porsche 928 > About the 928 > VIN Info>Vin Decoder' and enter your VIN number.

Then go to the 'gearbox info' page.... 'The Porsche 928 > About the 928 > Gearbox Info (viz)' and select 'gearbox by year' at the top. The chart will show the years/models at the top and gearbox type at the left; read down and over and you will see that there were 434 1986.5 928s produced with the manual (G28.11) gearboxes.