bushes

Hi all, I have been trying to diagnose the renowned clunking sound when releasing the clutch in 1st/2nd/reverse and whlst doing this, noticed my rear ARB bushes brackets/supports were totally rusted and seem unfunctional. As you can see in the photos, one side even looks like its had a cheap...

I'm probably being incredibly stupid (!), but what sized front and rear bushes do I need for standard OEM ARB's. Powerflex lists multiple sizes for both front and rear. https://www.powerflex.co.uk/road-series/products/Z3+%281994+-+2002%29-603/1.html

I'm about to change or upgrade (not sure which route now I've read some project threads!) the bushes and suspension on my Zed but I also saw a post with a picture of the boot area in someone's Zed almost rusted away (rear beam mount?). Three of the spot welds on the boot floor of my Zed (a 2.8)...