The 61 is the sales code number for a 383-2bbl or WHAT that car has for an engine.
The 889 is the assembly code or WHICH version of the 383-2bbl that car received. As they are different versions of the E sales code, the assembly code reflects variants of the engine that have manual or automatic transmission or with or without a/c as well as the body style (A, B or C) to which it belongs.
Code 889 is a 1969 383-2 C body automatic transmission non a/c assembly.
So, theoretically, there could be four different assembly codes for one E series sales code in each body but we know not all potential variants were available in all body styles.
The VIN code follows the sales code not the assembly code. This is why there is confusion about 383-4 VIN codes. Not all 383-4 VIN or sales codes are HP assemblies.