The block and head are interconnected through the timing chain/belt cavity on most engines. I don't want to say all, since I've not seen all of them. With that said, it is better to remove as close to the source as possible and multiple points have less restrictions.

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2003 X5 4.6is Estoril Blue
2005 Infiniti G35X
1972 Datsun 240Z
1991 Isuzu Impulse XS Sold
1972 Fiat 850 Spyder Donated
1972 Datsun 240Z Sold
1972 Datsun 510 Sold