Is this true

[Nikkia]

Can you put 4v heads on any year modular block whether it is a GT block or a 4.6/5.4 cobra/mach 1/ford GT/ shelby and vice versa?

[brown7]

the bolt patterns look similar between the 5.4 and 4.6..

also the timing cover/chains/guides etc will need to be changed.

[Mustangfreak]

I believe so, thats why they are called modular.

[SeeingRed]

Modular just means that a lot of the parts are interchangeable between motors. Doesn't specifically mean heads.

Some blocks will need some doctoring to accept a 4v head...it's not a straight bolt-on for 4v heads on all blocks.