On my swb S3 there's the bolts across the back between crossmember and tub. Four supports between the base of the tub and the chassis, two at the back, two at the front. Two bolts each side between tub, seatbox and the long sill mounting brackets going to the bulkhead. There are some bolts holding the aluminium sill to the tub, I think they're also the ones that mount two of the support brackets. There's a row of bolts between the seatbox and tub behind the seats. There's four bolts between the front of the tub and the chassis. I have early seat belt mountings which attach to the tub but you probably have brackets bolted to the chassis. The tank filler and overflow pipe has to be disconnected from the tank. Disconnect the wiring harness behind the RH light cluster. I think that's all....
Putting it back wasn't too bad, two of us lifted it on, a bit of wiggling around and it all lined up OK. I did replace a couple of the tub floor supports and added some extra plates across the corroded tub to chassis sections.