I couldnt on mine because I have a hitch and a 35 gal tank, I stayed with the single exhaust and added a flowmaster muffler to it. I wanted them straight out the back. I was told my only opinon if I really wanted duals, was in front of the rear wheels, I didnt want that.
I know of another vanner with my same van as mine that went with duals out the back, and a year later he removed it because he was tired of one side banging all the time, he was told that would be a problem before he did it. I know of another vanner with a maxi that didnt have a problem at all, I guess theres more room in the rear end of a maxi.
You might be able to get away with running duals out one side. Remember though Dave that your gas tank runs along the side not the rear like 71-97 vans. You may just have enough room to sneek a pipe past your gas tank and out the back. Or run the single back and split it in the rear...not sure if your spare tire would be in the way or not.
That's what they make door-mounted spare tire carriers for...
I have duals on both of my vans that exit out the side. My '71 has true duals. I bought a conversion kit from JC Whitney, and installed it without any problems. The only down side is the front section was 2" pipe to connect to 318 manifolds, the rear pipe is 2-1/4". Later I changed to a 360 engine, with 360 manifolds and upgraded the front part of the system to 2-1/4", included a X-pipe crossover to broaden the powerband. (It's just behind the transmission mount.) :rck:
My '78 has dual 2" tailpipes, that are replacement parts and clear a 35 gal. gas tank. Since it has a cat. con., the front section is 2" merged into 2-1/2" single pipe to the cat con, muffler, then split to the dual tailpipes.
Huh, this is the first I've heard of clearance issues on the vans. When I was going to get duals put on the Bronco, though, the t-case was in the way so I would have had to do some re-routing. I'm sure there's a way on these.