Ran across a question I can't answer

[SonnySideUp]

I was asked by a kid at work; he was about 25; and it's got me stumped. I can't give him any info other than "It's a 383" and I know there has to be more to it since I've built my share of nearly a dozen B & RB motors. He gave me the casting number off the block from the junkyard motor, 2568130-1. I've had quite a few 246- 383's but never a 256- so I tried to get the info. Talk about a ambiguous. I've seen the 246- listed as 59-71 ALL and the 256- listed as B-series. OK, we know it's a 383 but what Is the difference; but there's no other explanation. Aside from the -1 denoting what sand casting mold it is; what's the specific differences between the 246- & the 256-? Internal vs external balance, 2bb vs 4BBL, passenger vs industrial etc...? Does it make any difference when it comes to rebuild parts & performance possibilities?

 

[wagonman]

Go to 440 source they can tell you casting #s whats what.

 

[wagonman]

64-67 383.

 

[BeatersRus]

generic id code,whats the Top id pad stampings say??
that will get you a lot closer.
heres a copy of the numbers.

Decode the block casting number you recorded as follows: 2120329 = 383 RB (1959-1960) 1851729 = 383 B (1959-1964) 2128854 = 383 B (1964) 2532130 = 383 B (1965) 2568130 = 383 B (1959-1971) 2899830 = 383 B (1970)

Identify by ID Boss Stampings
Step 1
Locate the engine ID boss. If the ID boss is located on the block's right side just below the cylinder head next to the distributor base, then the engine has an RB (Golden Lion) block; if the ID boss is located on top of the block directly in front of the intake manifold valley, then the engine is a B block.

Step 2
As necessary, use a wire brush to remove dirt and grime from the ID boss stampings.

Step 3
View and record the top row of ID boss stampings (e.g., "P38", "E383", so on). Use a magnifying glass as necessary.

Decode the ID boss stamping you recorded as follows: M38 = 1959 383 (B block) MR38 = 1959 383 (RB block) P38 = 1960 383 (B block) PR38 = 1960 383 (RB block) R38 or R383 = 1961 383 S38 or S383 = 1962 383 T38 or T383 = 1963 383 V38 or V383 = 1964 383 A383 = 1965 383 B383 = 1966 383 C383 = 1967 383 D383 = 1968 383 E383 = 1969 383 F383 = 1970 383 G383 = 1971 383