Not quite sure I understand the first question--do you have any pics?
The reason you didn't see that brass bushing when you took the clutch apart is because it's located in the back of the crankshaft. The nose of the transmission rides inside this bushing, to keep it lined up with the engine during accleration, etc. I guess if you had a new crank put in, you won't have to worry about getting the old one out--just drive the new one in. Do you already have the motor in the truck? If so, replacing this bushing will be a bit harder than if it is still on the stand. Several ideas on removing the old bushing:
1. pack the cavity full of grease, find a rod, pin, etc. close to the same size as the hole, drive the pin into the hole, and let the grease force the bushing out. If the motor is out of the truck, this might work, but I've never been able to do it in the truck.
2. get a pilot bearing puller, like
this one from matco.
3. take a die grinder and grind the old one out, but just don't hit the crank!
