I have an ozone 500 with that ******** spring under the seat on the rear swingarm with the bolt through it.
I thought a rubber bushing set would work better.
So I bought these.
Vehicle Car 10 Pcs Orange Rubber Shock Absorber Bushings 10mm x 28mm x 20mm | eBay

These are a perfect fit where that spring should go and have a good solid feel to them. Very likely should give a wee bit without totally killing your back or being too soft or pogoing like a spring would.
Worst case, I can go back to the spring.
3 of those will work for the ozone 500 mountain bike.

I am thinking of making a metal clamp set to squeeze them tighter if needed. But if anything likely it will be pretty firm even with my 238lb.

Cool.
Srinath.