Tank Guard - Fitting

I`ve got a 1991 H reg Discovery 1 Standard, 200 Tdi, and i`ve got a galvanised tank guard in the pipeline to replace the standard land rover one. I understand to remove the old guard its a matter of removing four bolts and hey presto, but in the mean time whats supporting the actual tank while i swap the two guards over?

thanks

if i remember rite theres just two metal straps!
dunno if thats all that holds em in but you shunt have a problem droppin the guard down.