Eagle_Adams is an excellent person to purchase items from. Keeps you informed, ships quick and packs the items real well. Mahalo brah!!
GreaseMonky on the other hand is bad news!! Had to place Paypal claim for refund on this dude.
The book... How to hotrod & race your Datsun has some info on mini tubing. Here is a pic from one of the pages. http://www.datsun510.com/modules/Online_Manuals/how_to_modify/175.gif
I think the book is also in the manual section on the datsun510.com site.http://www.datsun510.com/
These bushings work great!!
http://www.racetep.com/datsunsusp.html
Or you could use the sold bushings if you don't mind the noise.
http://designproductsracing.com/510_RearSuspension.html