Will a 1991 5.7 liter Chevy engine fit into 1997 Tahoe?

While both are GM vehicles, a direct swap of a 1991 5.7L Chevy engine into a 1997 Tahoe isn't a simple bolt-in affair. The 1997 Tahoe likely has an OBD-II system, whereas the 1991 engine is pre-OBD-II. This means significant differences in the engine's computer control and emissions systems. You'd need a conversion harness and potentially a stand-alone engine management system to make it work.

Furthermore, there might be differences in accessories, mounting points, and other components that would require modifications or custom fabrication. While the engines are both 5.7L, internal differences are possible, affecting things like the intake manifold and other peripherals.

In short: It's *possible* with significant modification and likely considerable expense, but not a straightforward swap. You'd need mechanical expertise and potentially a professional to make it work.