Beginning with the Oliver No. 4, even-numbered Oliver models up to the Oliver No. 16 were exported versions of their odd-numbered predecessors. They were manufactured specifially to be exported to many countries in Europe, as well as some in Latin America. These models were never marketed in the United States, making them hard to find outside of Europe and Latin America today.
These even-numbered machines are nearly identical to their preceding odd-numbered counterparts with the exception of four additional keys and a wider base. The additional keys are for accents and other characters used in various languages. Depending on the language, some of these keys were made to be "dead" keys, meaning that when pressed, the spacing mechanism would not activate. This allowed accent marks to be placed in conjunction with other characters. Far fewer exported models were made compared to their odd-numbered counterparts. Up to and including the Oliver No. 10, the even-numbered Olivers follow a different serial number scheme. Models 4, 6, and 8 have a "D" prefix while the model 10 has an "R" prefix.
The Oliver No. 4 is the first Oliver model that was manufactured solely for distribution outside of the United States. This model was introduced in 1904, three years after the introduction of the model 3.
The Oliver No. 4 began a new export serial number scheme starting with D001.
Following the Oliver No. 4 in the export series is the Oliver No. 6. Since the model 6 is based on the model 5, the model 6 received the same improvements the model 5 received throughout its production run.
I have the second and third earliest Oliver No. 6 machines I know to exist- serial numbers D4301 and D4756.
Based on the Oliver No. 7, the next exported model following the model 6 is the Oliver No. 8. Since relatively few Oliver model 7 machines were made, in contrast to models 5 and 9, one would expect even fewer Oliver No. 8 machines were produced; and this is true. I know of seven Oliver No. 8s to exist, five (possibly all) of which are less than 300 serial numbers apart.
The earliest known model 8 in existance is D31245 and the latest is D31445. The earliest Oliver No. 8 is over 10000 serial numbers higher than the latest Oliver No. 6.
Following Oliver No. 8, the next exported model is the Oliver No. 10. Since the model 9 is the most common domestic model, the model 10 is naturally the most common export model. Most (but not all) Oliver No. 10 machines were exported to France and England.
The model 10 continues with the export serial number scheme, but with an "R" prefix instead of "D". The earliest known Oliver No. 10 is serial number R41001, which may be the very first model 10 produced.
The Oliver No. 12 was the last export model manufactured in the United States. It is based on the Oliver 11.
The Oliver No. 12 unusually does not continue following the export serial number scheme. Instead, the model 12 serial numbers are intermixed with models 11 and L-12. I know of six Oliver No. 12 machines in existance.
When the Oliver Typewriter Manufacturing Company opened in England in 1928, they introduced the Oliver Nos. 15 and 16. These British Oliver models keep the same gloss black finish introduced on the Oliver 11 and 12. The most noticeable improvement was made to the ribbon holder lids - they are now flat and pivotable so that they would not get lost. Unfortunately, it took over a dozen models for this change to be made.
The Oliver No. 16 serial numbers have an "R" prefix. It is unclear as to whether these numbers are intermixed with the Oliver 15 serial numbers or not. The first Oliver 16 may be R1001.