The reason the newer unit don't have the swings that the older units do, is when the units went to fuel injected, a baffle was installed into the fuel tanks to keep more fuel around the intank fuel pump. This helped reduce the fuel movement reducing fuel gauge swings.
I had 3. An 85 GMC Gypsy extended cab that I bought in 94 with a 2.8 L that had a broken crankshaft. I drove that until 2000 when my wife took the engine out again. I then bought a loaded 92 extended cab Sonoma with the 4.3 that I drove until 2008 when it burnt up on me. I then bought a 93 S-10...
Another difference was in the fuel tank selector switch. The carb units had a switch that just clicked from side to side. The inj units had a switch that was spring loaded for a momentary contact that had to be held for a second to switch. The switch also had to switch power to the fuel pump...