Stock exhaust diameter?

[barmanvarn]

So here's the deal. I've got the engine running, but still need a gas tank and brakes.

The problem right now is when I have the engine running, I'm getting smoked out by the exhaust as there is no pipe coming out the back of the muffler. (I think there's a pipe nub left, but not sure as truck is 100 miles away).

Rather than add a new pipe (with the proper bends), I was thinking of just attaching flexible exhaust pipe to the muffler so I can vent the exhaust all the way to the rear.

Questions:
1) Anything bad about this approach? Again, truck isn't rolling now so it's not like I'll be driving down the road like this.
2) What diameter is the stock exhaust?
3) I assume the diameter of flexible exhaust pipe is the internal diameter? Meaning, it goes over the stock pipe? If there is a nub left, I was thinking I could slide the flex pipe over it and clamp it down. If there isn't a nub, I can go buy a 6" length of pipe to use.

thanks