JohnM wrote:

Just fill the tank with water..

Seriously, if it's not leaking and you're not putting sparks in the
filler neck you're ok. If there's any concern about sparks getting in
the filler neck or tank, making sure the tank is all the way full
eliminates the possibility of explosion. As always, keep a good
extinguisher or two handy when working on a car.

John

i've decided to just take a few extra minutes and take it off first (at
least this time the bolts aren't all rusted on). Plus, I think my welds
are better when i can position the work rather than having to position
me.
thanks for the suggestion, it sounds wierd to make sure the tank is
full, but it is true that the fumes ignite, not the fuel.

walt