Help in decoding block numbers

[mrmedisoft]

OK, I have 2 engines with my 1970 Challnger RT 440. The 440 6PAK block number 2536-430-10 was professionaly machined and totally rebuilt at a local speed shop - for $5K I might add!And the 6 PAK ain't rebuiltyet either! The other engine is supose to be a 383 block number 4006640-440-10, but it is physically larger and heavier than the 440 short block. Just what do I own? And I also have 2 rear-ends. One is supose to be a Dana 4.10 and the other the stock 440 6Pak rear-end 3.8 are something like that. Is there anyway to tell what the rear-ends are from external stampings or other clies, or must the be rear-ends be cracked open to see which is which?

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[Jeffmarble]

2536430 Chrysler - Dodge - Plymouth RB 66-72 440is the first engine
the second i could not find a casting number for that
4006630 Chrysler - Dodge - Plymouth RB 78 440is the closest i found this is probably because they stopped production of the 440
864006630440 CID
1978Body = RB
the engine casting seems to denote that after the first set of numbers the - it says 440 than its a 440 not a 383
now heres the issue you stated its physically larger and heavier. now if this is perhaps a later model motor for industrial use it could have forged internals which could slightly make it heavier. but not noticably. hemi heads on there for some weird reason? take pictures id like to see this block i searched the intire internet and could not find info on this block with the casting number. do u have head casting numbers?

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[mr340]

The 4006630 was a 440 casting from late '75 thru '79.
The 2536430 is from '66 thru '72
3698830 is from '73 to early '75
I find no reference to a 4006640, only the 6630 and a 6530 (which is a 400 block '75 to '78)
That doesn't mean your numbersare wrong, but as stated above it may be a motorhome or industrial or even marine block.

[dodgebrothers]

As for the rear ends mentioned. Is your Chally a 4 speed car? If so, only Dana's came w/ the 4speeds on 440 or hemi.