Ok, here goes. I'm tired of waiting on the welder to show up so I'm thinking of doing it myself. I'm used to welding on heavy steel not thin fenders. My mig welder with argon has .30 wire in it. What size wire should I use and how do I prevent heat warping the fender? I have the patch panels. Do you butt weld it in place? I'm scared of cutting to much out of the fender also. Any pictures of "How To" would be great. If somebody can tell me what the heck to do I'll see if it's for me to try. Thanks, in advance.

I'm assuming the patch panels are for replacing the entire lower fenders?
I've always found that using as much of the original fender's steel yields the best results and saves a lot of work and time.
How much good metal do you have left in the originals? If you just have a hole in the center, I would just cut out the rot, make a patch and weld it in. The new pieces aren't shaped the same as N.O.S.

The best and most professional method would be hammer welding the new patches. It takes talent and practice to pull it off.
Mig welding a piece in isn't all that hard. Make it as flush as possible, not creating any high spots. Do a stitch weld alternating the heat spots. Keep the metal cool so it dosen't warp.

As far as how much orginal metal is left. On the ringt side the rott is about 8 inches high and not round it vairies from 4 inches to 7 inches wide at the bottom. On the left side it's about 5 inches high and 6 inches wide. The patch panels are 9 1/2" from the top to the bend at the botom. So I guess I need to use the whole panel.

do some practice welding first, good alignment before welding is key, tack the panel into position and monitor the fit as you go. skip around with small welds until the complete seam is welded. Grind very carefuly to avoid any heat build up.