Is it a constant leak even after parked overnight, or does it only leak with the engine running?
I have a 97 blazer 4-door. I went through this in April 2010:
If it's constant, drive it to 1/4 tank or disconnect feed line at fuel filter and run the pump for a while (put into a gas can, obviously). It's easiest to jumper the relay socket in the glovebox or the control wire that goes to the relay from the ECM (not sure which computer the 96 has, might be different than mine). On mine, it's pin1 on C4 of the VCM (dark green/white-stripe upper drivers side VCM plug). See http://www.justanswer.com/questions/1y110-i-have-a-1997-s10-blazer-with-a-4-3-with-csefi-the-in-tank
I had three leaks pop up on me this year, each one caused by the previous! First leak I encountered was a rusted main fuel line under the rear passenger door-- just started leaking one morning after I started the engine. It was a relatively slow leak (1 drip per second or less, wet frame rail)
A few days after redoing the lines, it started leaking again. I thought I botched the new lines, but there was a small set of rust pinholes just above half a tank that had cracked open when I jacked the tank back up and the rust layer flaked off.
If you have to do your steal lines, I'd recommend putting a new tank on at the same time if it has any signs of rust. Use the original blue fuel tank O-Ring. The O-ring that came with my $110 carquest tank didn't seal correctly and it leaked out the seal when I filled up! (the THIRD leak..)
My front tank strap retainer bolt sheared apart the first time I dropped the tank because the nut was rusted on. If this happens, you can maybe weld it using a new bolt, or go to a GM dealership and have them get a new bolt.
The lines are a also a GM-specific part. I decided they were too expensive for my old girl (over $300 for the full set of evap/return/feed), so I bought some 3/8, 5/16, and 1/4" steel brake/fuel line and cut to length with a tubing cutter. It bends no problem. I re-used the ends of my fuel lines (still good, not rusted) and connected the GM quick-connect ends to the new steel lines with high-pressure fuel injector hose (expensive stuff!) and fuel line hose clamps (all of this came from Advance Auto).
If you only have to do the tank, carefully inspect your lines and consider replacing them as preventative maintenance. My evap lines were so brittle they broke apart when I touched them.