my tanks were so rotten I thought they were animal feed troughs !
I set mine in expanding foam which has made the sill a lot firmer too. Make sure you have enough clearance for the top of the sender unit when making new, mine were very close in the end.
I was talking to Gary the other day and he had just got a pair remade, he was happy with the work and the price, might be worth asking?
Hmm, i'm sure the foam and wooden blocks will work, but i don't really like that solution. The expanding foam will fix the tanks in place forever?
I was thinking of some metal straps that would pull the tanks tight to the chassis, all covered in thin rubber.
As for the needed clearance, thanks for the tip. I think i remember someone's alloy tanks didn't fit the sills and had to be altered.
Not that my tanks are that rotten :) When i bought the P2, someone already built a third tank in the boot, Austin Mini.
I'll ask Gary about the price, but i'm afraid shipping would be very costly needing two pair. My brother can have the aluminum parts laser cut and bent after i put the tanks in 3D.
Hi Erik.
Same for me. Mine were just sitting in the sill with foam under which caused them to rot out completely resulting in new ones having to be made. I posted a picture of the new ones some time ago. I had them fitted with a weld in ring to take VDO dip senders and AN6 outlets. IIRC, they cost me £600.00. Like Nigel, I was intending to use expanding foam to keep them in place. I also think Nigel posted a picture with the tank sizes which might help with your 3D rendering.
I to am with Frank. Blocks of wood to stop movement and a modern fuel safe foam or fuel safe rubber under the tanks or added to blocks under the tanks to support them. The type of rubber I was thinking of its the strips, they use on truck fuel tanks under the straps. A couple widths would be about right. I could find Volvo ( only as I work for them)truck parts numbers and pictures if you thought may be a way. Expanding foam may put stress on the area. Or if you have read my latest in traction Ken Wilson found. Vauxhall Viva ones fitted in the boot fit well.
I think Erik is on furlough 
