[djpateman]

Pete, no problem, and I like trying to get these details straight. Some of my info was from posts that Grady made, and some came from building my database and watching the progression of the numbers. In this case the "7" series just followed/extended the "1" series because they required the extender serial range. This was not unique with the transmissions either. Here is the list of 1970 911T engine numbers:
911/03 6100001 6103000 ROW
911/06 6103001 6103230 ROW Sportomatic
911/03 6103501 6104547 ROW
911/07 6105001 6107999 North America
911/08 6108001 6108374 North America Sportomatic
911/07 6108501 6109955 North America
For both the 911/03 and 911/07 engines they underestimated the ranges they would need when they set the pattern up, and had to add an extended range for both types. They almost ran out of the extended range again for the 911/07. For 1971 they changed the pattern a little so as to avoid needed two serial ranges for one engine type.