Hi 63tb,
>Oh, I thought the engines were identical but the reduction gear boxes were geared in reverse.
I believe that was the more common way to do it, but the Allisons appear to have been complete mirror images indeed.
The German DB603 was developed to be right-hand or left-hand configurable, but apparently the advantages were found to be marginal so this feature was not used in practice. Of course, the German war industry was under much heavier strain than the US industry, so they were probably more conservative about increasing production complexity.
Regards,
Henning (HoHun)