3849852 - Block Casting Number - 1957 -1966, 283, 195 - 220 HP, 2 bolt main, car & truck
F0404DE - Engine Assembly Code - F = Flint (vehicle assembly plant), 0404 = date code, April 4, DE = Engine Suffix Code (this particular code (DE) was used in two years during the Block Casting Number year range, see above), 1958, 283, Powerglide, Bel-Air or Impala (1958 was the first year for the Impala), or, 1962, 283, 195 HP, Powerglide, a/c, Nova, (1962 was the first year for the Nova).
So, what do you have?
A pretty interesting engine!
Could have been in a 1st year Impala, or Nova!
How cool is that!
An Engine Partial VIN Code would have nailed it right down to an exact car.
This number would have been stamped on the front passenger side, just under the Engine Assembly Code, probably behind the alternator.
The Engine Partial VIN Code was suggested by the federal government in 1969, to begin in the 1970 production year and required was by the government starting in the 1972 production year.
Unfortunately, it was not stamped on the engine in the production year range of this engine.
So, you have an early SBC, 283, possibly starting life in a 1st year Impala or Nova.
It would be interesting to check the head casting numbers to see if they are possibly the originals, but probably no way to tell exactly.