body filler recomendations?

[Chevy305]

I want to redo some seams on my truck now that I have a welder and after I weld it up i want to smooth it out. I found this and it looks like what I need:

http://store.summitracing.com/partdetail.asp?part=MDS-US14060

 

[bigblock72]

What seams are you filling? Most likely going to want to go with a regular filler, maybe some fiberglass reinforced (Mar-glass) filler if it's a high stress area or an area that's going to get more than an 1/8" or so of filler.
http://store.summitracing.com/partdetail.asp?autofilter=1&part=MDS%2DFE282&N=700+4294759073+115&autoview=sku regular filler
http://store.summitracing.com/partd...MDS-US24035&N=700+4294759073+115&autoview=sku fiberglass filler

I personally have never found a reason to use that nasty metal filler.