rear torsion bar bushing

I am about to change the rear torsion bar bushings but my mechanic told me that the bushing and the spring plate are intergral.
Therefore to change the bushing i need to also change the spring plates.
Any thoughts?
My car is a 70 S.

He is not entirely correct. The bushings are bonded to the spring plate but you can melt them off and glue new Neatrix bushings. This would be a great time to upgrade to adjustable spring plates which you can get used for about $100.

Here are a couple of links to check out

Link 1

Link 2