the only thing, parts, on the 1970 and 1971 street hemi Carter AFB was the fuel vapor return vent on the rear carb. Everything else, jetting, metering rods and venturi were the same as the 1968,1969 street hemi Carter AFB four barrel carbs, I raced both the early, pre 1970, and the later 1970 and 1971 street Hemi cars in NHRA stock

This is not true. 68 had different jetting and meter rods for front. 69-71 used same jets and meter rod, but 69 and 70-71 used different primary venturi and had different idle jet.

For the rear, the 68 manual had its own set of venturi for idle jet and air bleed. 68 auto and 69 where the same but different idle jet than 68 manual or 70-71. They also changed idle air bleed. 70-71 used different venturi and had different idle jet again.

The FSM show the jets and metering rods the same from 1966 to 1971 on the street hemi carbs

Not the FSMs I looked at. Plus the 66-67 are way different in being Air bypass carbs and Non Emissions (Cap) carbs. There are some errors in the FSM too. 67 had cap hemi carbs for CA only, 68 was first hemi carbs CAP emissions for all states. 69 they tweaked the idle emissions, 70-71 are the same but tweaked the idle emissions again, and richened the front carb idle.

I have stated this before, the 68-71 Rear hemi carbs are unique in they have secondary non adjustable idle circuits. Probably had to do that for distribution purposes as they were leaning out the primary idle circuit of the main rear carb. I would love to have seen the carter and Chrysler Hemi dyno data as they made these changes. The carter technical manuals are the real source on these carbs. Carter provided all the bleed values, fuel and air for the venturis.

I never really got into all the secrets, tricks, and main reasons for modifying them internally other than, jet and metering rod changes only and making sure they were wide open at full throttle