Roger, my real interest is 2x3 Graphics, not the larger sizes. I once collected serial number data from the non-book for 2x3ers. I don't know whether 2x3ers' production history matches that of larger sizes of Graphics and the non-book lumps production from 2/47 - 2/50 so I can't report exactly how many 2x3 Pacemakers were made between 2/47 and 8/49. My best guess is that around half of the 2x3 Pacemaker Graphics (Speed and Crown) were made between 2/47 and 8/49. None shipped with a Graflok back, some may have been retrofitted with a Graflok.
A comment on the non-book. It shows two series of serial numbers for Pacemaker Graphics. Graflex started making Pacemakers under their old s/n scheme, in which serial numbers were assigned sequentially and a serial number carried no information about the product to which it was assigned. Some time in late 1947 Graflex switched to a new s/n scheme, set aside huge blocks of numbers by product. Sales weren't as expected and few of the serial numbers that had been set aside were ever used. The book reports s/n ranges and the dates they were released to production, but gives no detail about when serial numbers released between the start of the new numbering scheme and 2/50.