Should be on the right side of the neck.

 

Your '75 won't have a modern VIN, they weren't introduced until a few years later, 1981 IIRC. You should find a frame number as Billy describes. Modern VINs are also displayed in a shortened form as the engine number, but before that the engine number was commonly completely different to the frame number. If your bike has been repainted over the years you may have to scrape the paint off to read the number clearly.

 

In the US I believe Harley started putting the VIN on frames around 1970. My 71 Superglide had the VIN on the frame.
I believe they went to the 17 digit number in 81 but Harley put the # on the frame way before then.

 

You may be right, however the expression VIN has probably been applied retrospectively, rather than literally. Bikes have had a frame number since Noah built the Ark and it would be easy to call that a VIN!

 

No 1969 and earlier Harley did not have a frame #. There was none on my 64 Panhead, The VIN was stamped on the engine cases with the first # being the year. 1970 is was when they went to alternators and changed the engine cases and started butting it on the frame and cases. I cant remember crap this morning.

 

VIN will be on the pad on the right downtube near the neck. Could be very hard to read as they get painted over. Do NOT mess with it, even if it's hard to see being painted over. Any alterations make it look worked over, and the cops will hassle you if they want. Not fun explaining to a cop younger than you how classic VIN's work for Harleys... The red box is where it is on my '72 and should be for yours as the frame didn't change.