that number designation is how Hurst identified them;
The "330" number is the GM designation.
As a matter of comparison, Borg Warner (OEM parts manufacturer for alot of GM's stuff) designated the Saginaw three speed as a "301", and Muncie three speed as a "306".
The confusion behind OE vs aftermarket designation numbering is why people often refer to transmissions by their common order code (or RPO);
The trouble with RPO's is that even with the same model vehicle, year after year the same RPO could be a different sourced part.
Numbering aside, that chart does correctly show the single top/centred bolt for the Saginaw;
Side by side, they are
very easy to mistake for each other.
If nothing else, us continuing to talk about this keeps your thread current - and easier to find by a potential buyer
