Just dug out my 73 Sportster. Serial # starts with 3A, how do I tell if it is an Ironhead or not? Am asking cause don't know if parts are interchangeable or not.

 

Google images, search for 1973 Sportster. Do your heads look the same?

Or you could post a pic here.

 

3A is Electric Start Last 2 will tell you the year. Should be H3 for 1973 And 73 is a Ironhead
57-85 were Ironheads

 

I had a 73 but your pic is kinda dark on my phone. Is it right side shift? 73 1000 was the last year for right side shift. Iron heads.
AMF bought them out in 74 i believe.
Wish I still had that bike. It was a screamer and I had it lookin' and soundin' real nice.

 

1974 is last year of right side shift.
AMF bought HD in 1969. HD bought it back in 1981