Engine: differences in part numbers

[arkusvt]

can anyone enlighten me of the following differences, all for an r-2 avanti?
water manifold, book says should be 1555739, i also have 1555738, they appear identical
supercharger bracket, book says should be 1556852, also have 1556853, appear identical
supercharger idler arm, book says should be 1556855, also have 1556856, appear identical
intake manifold, book says should be 1557843, i have 3, one taken from a lark, one from an r-2 avanti and one from an r-1 avanti.
they are ALL 1557144.
research today came up with nothing to solve any of the differences. sure would appreciate any help. thank you!

[Alan]

Lark and Avanti are 2 completely different manifolds. We need pics. to see what is going on.

[Skip Lackie]

How do you know the part numbers of the items you have? Are they still in their original packaging? The casting numbers on many cast iron parts are often one digit off from the part number(s). And the same basic raw casting was often used for several different part numbers.

[karterfred88]

Since the intakes were "taken from" you must be referring to a casting number since there is no part numbers on them, the casting number is 1557144 at least on my R2 Avanti. Rest are probably casting numbers as well which may have no true reference to the actual part number.

[arkusvt]

well that clears things up quite a bit! was thinking casting numbers were part numbers. thanks to you and skip for the education. now, how would one know if an intake was for an r-1 or an r-2 short of being an "expert" given the same casting number? thanks again.

[StudeRich]

The only difference between '63-'64 259/289, R1 & R2 AFB 4 Barrel Manifolds will be the Secondary Throttle Bore sizes, just measure them.
Large, Larger and Largest!

[64studeavanti]

R1 intake manifolds do not have transfer slots between bores. R2 and 'regular' manifolds do.