It looks a lot like an early 90's 5.7, '92 or earlier IF that is the original distributor, but it could be a mix of parts 'n' pieces too. The layout looks kind of like an Impala, but I'm drawing a blank on that air cleaner, never seen anything like that on a Chevy...assuming it's out of a Chevy at all, or even a car for that matter. The v-belt setup is weird, too, almost like it's off earlier vehicles. GM was using ribbed belts even in the mid-80's. The S-10 setup was popular for rods, but I'm wondering if they swapped in a beefier axle setup. 4.11 is great for burning rubber, but kind of sucks on the highway, even with OD. The casting number is always on the left side (driver) of the engine on the bellhousing flange.