The previous owner had a RW products egt gauge installed in the turbo down pipe. The probe/fitting is 1/2 in diameter with a 5/16 thread. I drilled the original cast iron manifold out with a 27/32 drill bit. I tried tapping the manifold and its only tapping on part of the hole. Meaning if looking from towards the firewall its got threads from roughly 8 o'clock to 3 o'clock. I am moving from Ohio to Arkansas this Friday and need this truck.

Thanks guys !

 

It sounds like you're using the wrong size tap.
For a 27/32 drill it should be a 1/4" NPT tap.
Far as I know pyro probes are either 1/8" or 1/4" NPT, nothing else.