Quick engine family ID tip
Count the valve cover bolts.
Five bolts- FE (352, 360, 390, 427, 428)
Six bolts- Windsor Small block (260, 289, 302, 351W)
Seven bolts- 385 series (429, 460)
Eight bolts- 335 series Clevelands (351C, 351M, 400)
There is an exception to this 'rule', namely the Boss 302, which is a Windsor small block block with Cleveland-style heads - but that is another whole can of worms.
Both the FE series and the 385 series have been referred to as 'big blocks'. It is wise to ask when someone says 'big block' as to what in the heck they are talking about! Then we get into the discussion of whether or not the Clevelands are small blocks. Some say yes, some say no.
Then we get into the differences that can be found
within each engine family.
351Ws have a taller block than other small blocks. Since the block is taller, the intake manifold is wider. Then there are the 12 vs 16 bolt intake manifolds....(I think that's right. I don't mess with small blocks

: ) 351Ws use bigger head bolts. 351Ws have a bigger diameter oil pump drive shaft.
351Cs are different from their 351M/400 counterparts because they use the shorter block. 351M/400s have a taller block. Easy way to tell the block is look at the distributor hole. If the distributor mounting surface is flush with the intake manifold surface, you have a 351C. If there is a 3/4" raised wall at the intake surface, you have a 351M/400. 351Cs also use a 'normal' Windsor small block bellhousing bolt pattern. 351M/400s use a taller pattern that is the same pattern as the 429/460s All 351M/400s were made as 2-barrel engines, too. The 351C came either way. The 351C four barrel heads used much bigger ports than the two barrel.
Then there are the open vs closed chamber heads. Then there are the non-adjustable vs the adjustable valvetrain heads. Aaaauuuuggggh! ID-ing Ford engine parts can be a real pain in the wallet if you
think you're getting one part when you actually bought something else... Quite maddening!
Hope this helps some of you!