Boy - am I happy I found this forum

I've just imported my beloved '04 ute from the UK and found it's too corroded for entry certifying. It's only done 55k miles so the engine and bodywork are good but the chassis is corroded to hell (guy before me must've launched his boat with it?). I'm told I need to get it a new chassis. Its the KDN165R-PRMSYW model and I wonder what suitable used models would fit the bill here in NZ? I'd be grateful for any help/advice and (if poss. as I'm no mechanic) what kind of job difficulty/cost am I setting myself up for if I try and switch the chassis?
Cheers
S