Looking at the pics I cannot tell much as the welds (beads) have been ground off.
If you are blowing through, making holes there is too much heat. Best easiest simplest way to make it easier especially for a novice is use a copper backer. The copper plate will draw some of the heat away and prevent blowing holes. You can even place a copper backer behind a big hole and fill the hole. The copper will not melt and mix with the steel.
You can get the plates at welding supply they are expensive because they are copper. Copper is soft so you can bend to the inside of the curves. Eastwood has some with magnets that will stay in place.
http://www.eastwood.com/4-and-8-inc...287&gclid=cpkfibwg-rwcfucv7aodcxia7gEastwood (and welding supplys) also have devices like this for small locations.
http://www.eastwood.com/magnetic-hole-plug-welding-tool-not-for-gas-welde.htmlIf burning though the metal, especially the original cab this will help a lot.
Also, the smaller the wire the less the amperage needed so less heat, less blowing holes and less distortion. Wire sized .023-.025 is really best for welding 18-19ga sheet metal.
Hope this helps
Mikey
