Where to find front/rear hd leaf springs for '85 Marathon gas

[Shugs]

I posted the other day asking for suggestions to handle the additional 350 pounds or so I'll be adding to my '85 Marathon gas cart by turning it into a steel dragon art car for Burning Man.

In the end, I've decided to just get/install new hd leaf springs (front and back) and get some new tires (I'll post a question about tires separately after this!).

I have looked *all* over and I can't seem to find hd leaf springs for my cart. I've seen some listed for newer Marathon gas carts. And some for the same vintage Marathon electric carts. But none that I can find for an '85 Marathon gas.

Where can I find the parts I'm looking for??

Can I use front and/or rear hd leaf springs for a different model?

Also, while I'd prefer to just get the "kit," if I do need to buy things separately, what do I need other than the front springs and rear springs (I think maybe some kind of "bushing," whatever that is?)?

Thanks,
Shugs