Ok... Well the headers you're looking at are for a V8. So, no they won't be an easy install.
I have a set of edlebrock direct fit shortys on my '94 5.7, and they were "easy" to install i guess, as long as you have a well equiped garage, with air tools. Your truck, being a 4.3 is pratically identical to a 5.7.
The important issue with "direct fit" headers is where your stock Y-pipe bolts up. My headers were almost identical to my manifolds, so no custom fit was needed.
On the one you posted (link didn't work for me, i cut and pasted the item #)
http://cgi.ebay.com/ebaymotors/ws/eB...tem=7968191666 It has a weld on collector at the end.
Unless you're proficent with a welder, or plan on bringing it to a custom exhaust shop - not the way to go. Spend some time on
www.edelbrock.com, research their header part numbers on google, and maybe you'll find it cheap. I bought mine at
www.summitracing.com, along with a new y-pipe, to ensure a trouble free, rust free install. The performance is very noticable. Good Luck!