a friend of mine made it, basicly steel box made to resemble a 50. with added rivets, handles and such.
the barrel is exhaust pipe.
I read in another post you wanted to turn yours into a military jeep,you got a nice jeep there, a lot better than mine when I got it. I bought mine just to plow with it, but after getting it running and roadworthy I decided to make it a Navy jeep. My dad was on the SS Saltlake City. Plus, every one has an army jeep, just needed to be different.
There's a site with a lot of info specifically for the 3B, not sure if you've seen it.
CJ3B Bulletin Board
The CJ3B Page
the guy that heads it up Derek Redmon is from Canada also.