in the early 70's my 59's seat was held on with a rope but that was also when if you rode a bike you were low life hippie or worse

 

Nowadays it's duct tape and zip ties!

 

This old thread was helpful.. My seat nut actually broke on me.. maybe it was overtightened.. New bike and I've been swapping between the stock seat and a sundowner..

I used some wire I had for a garage door opener to pull the nut up threw the fender. Then I attached the retainer clip and simple pulled the wire on threw.

 

Here's a link to a video on using a wire for install.

 

follow the video, great tip