While going through all these motions I have noticed that my muffler is looking like it's about to explode...and chinked out and flexed.

I was wondering about running duals back from the stock manifold.

Questions...
1. what size is right? Someone said 2.5's were the best.
2. What type of muffler gives the best subtle sound and quality performance. Because I am using it for travel and camping I don't really want rumbling flowmasters but some aggression would be good.
3. I have an underbelly propane tank so running a pipe down the passengers side isn't an option (I don't think). Can I have both pipes dump in front of the driver side rear? Or behind. But..together?

Thoughts? He quoted me 350 aprox...not sure if that is a good price or not. (haven't shopped it around)

For a mostly stock 360 engine I'd go 2.25" exhaust. 2.5" is freer flowing, but not necessary for the small backpressure difference to 2.25. Smaller pipes will be a little quieter too and still give you plenty of giddy up and a nice tone. Largest length free flowing muffler you can get under there would also help keep her quieter but still, being a free flowing type (Magnaflow, Flowmaster, Dynomax Ultra-Flo, etc.) will make it noticeably louder than stock. GOod luck!

It cost me about the same to have true duals put on my 85 and the shop I used did a fabulous job. I think my pipes are 2" but I'm running a 318/2bbl.

How much should you pay for some like that?...I'm considering that on my 94 as well.

Pretty much any auto has the exhaust plugged up from the factory due to people driving them and not keeping them in tune.

Any free flowing of the exhaust is going to help in performance as its kind of like taking the plug out of the exhaust. So re leaving any back pressure due to multiple chambered mufflers will help. 2 1/4 to 2 1/2 would do the trick.
Get Aluminum pipe and pay the extra cost or you will be back to the exhaust shop before you know it.

for a stock motor i would do a 2 1/4 true dual, too much bigger and you lose too much back pressure, which means you lose off the line grunt(torque). a good 1 in 2 out Flowmaster 50 or 70 series would keep it reasonably quiet, and still sound good. You can have your exhaust man run both pipes down one side then split them over the axle. I recommend side dumps or rear corner dumps on an older van because you will get a back flow of exhaust gas in the back doors if the seals are bad or you have pop out windows.

I recommend 2 1/4" pipe from engine to mufflers, 2 1/2" pipe from mufflers to exhaust tips. Your exhaust will stay cooler during long hill climbs without killing torque.

Yea, I want to change the exhaust. Some dude cut the Y pipe off and put in 3" pipes and Flowmasters without running to the back.

Anyone know the diameters of the original Y pipe on a '77 B200 318 engine, 109" w.b.?

I was thinking about running 2 1/4" with some cheap turbo mufflers and have them exit at the back sides. Gas tank might be in the way, though....

Walker quiet flow mufflers are great for quiet sound but free flowing, for a mild 318 with dual exhaust I would say 2 or 2.25 inch exhaust. Or, I say run a single 2.5 inch the whole way back. Same low restriction exhaust, less weight, no issues with running next to the propane tank on the passenger side.

I had this work similarly done to my 99 ranger 2.75 exhaust all the way with dual flowmasters and no cats. Only cost me 250 only problem they used aluminum piping for fence posts so it had a nasty tin or metal ping like sound while rumbling/farting. But that's the difference between a V6 and V8.

Good price at 350 for a job like that as long as it's done to your liking. If anything trial and error. Sometime next week I'll be cutting my muffler off and putting in a straight pipe. But I gotta keep the cats this time, smog laws are stupid and make for bad performance in any vehicle. Anyways, I like it loud!