I bought a kit of one of the reputable sites, had a lot of problems with one pipe. It was rotated 90 degrees and stuck way up high, would nearly hit the cab. A friend with a welder and three cuts and two splices later, it's where it should be. I've got a shelf with all the stuff I should return, but I hate doing that. So fix it was my path.
Ordering the parts was difficult. The truck is 1980, the engine is 1991, the heads vortec (brand new). Is that round, oval, square? You should find a kit much easier with all stock. I also was looking for a good sound, but not too loud. The non-kit-standard mufflers I chose contributed to the difficulties. Self inflicted. Keep it simple. :-)
It sounds nice, you'll be happy.
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