speedo cable doesn't fit

Mine is a 75 with a 904, but should be the same. I Looked up 73 with a 340 (should be 727) on their website and it gives same part.
Part Number: 6151659
Product Line: Balkamp
IMPORTANT INFO: 68" Long
Price: $ 19.39 /ea
I tried to measure the knurled part on mine, looks like About 1-1/4 outside