1970 Dart 340 Swinger Lower Left Hand Ball Joint Part Number.

Is the car still small bolt pattern? Drum and disc have a different part number. May have received a set of drum lower ball joints. Uppers are the same.

If the upper is too big, you may have received the 73+ upper/lower set.

Small ball joint numbers
Upper - Moog K704
Lowers
k7023
K7021

That's from memory.... YMMV :)