[2000 Chevy Dually]

I had to change the hydro-boost unit on my 2000 Chevy Dually with a 7.4 liter engine. When I put the master cylinder and the required hoses back, I tried to get the vehicle out of the park position while stepping on the brake pedal, but it would not shift into any gear. Any help would be greatly appreciated.
Thank you
Bob

 

[bigblue4x4]

do your brake lights work?
if they do I suspect its the park/brake interlock
they are notorious for failing and not letting you go out of park
look for a black plastic box with a metal bar coming out if it attached to the shifter linkage
its under the dash not in the column
pop the metal bar off the ball and you will be able to drive the truck till you replace the lock