I take it you are using a mig welder with shielding gas. If so you might want to try a wire called "Easygrind". It is made specifically for body work and grinds much easier than standard mig welding wire. It is a little pricey, around $40.00 for a 11# spool, but well worth the price if you are replacing very many panels. One place to find it is weldingsupply.com Part # for .023 is 130tf43, and for .030 is 130tf44. The wire is made by spoolarc.
John
