I have a 1988 f150 300 6 4x4.. the previous owner did quite a bit of needed maintenance, one of the things he did was replace the exhaust manifold, when I bought it today it was leaking. he said when he installed it it was fine , and then told me that after a new installation gaskets/manifold that the bolts needed to be retorqued,after a period of time is there any truth to this? and if so how the world do I get in there to do so? thanks in advance

 

If it's the pipe to the manifold, that may work.
If it's the gasket between the head and the intake/exhaust, no. You will have to replace the gasket

 

its hard to narrow down where its at ,,, whats a good method to find the leak?

 

If it's the manifold to pipe, if you put your hand near (not on) the area where the pipe goes in, you will feel a hot air leak, will actually puff at your hand Be careful, very high temperatures her, and you can get burned very quickly
Manifold gasket on an efi truck Is a bit harder to look for. If you can get a mirror and look under the maanifold, and ontop the manifold bu the head, you will see some carbon traces
Sometimes if you rev it hard and let right off, you will see fire come out.

Find out from the PO if he replaced the intake/ exhaust gasket, or just worked on the pipes