You shoud be able to swap the tail housings and get it to work.....

 

77&79, I sure wish it had been as simple as changing the tail housings. As it is, in addition too changing the tail housings, I had to disassemble both trannys, and swap the output shafts. It really wasn't that bad of a job. It only took about half a day to disassemble both trannys and reassemble one.

 

Alright let's get to work! Any time I can help a marine I'm all over it. My grandpa had serve 3rd divison 3rd recon in WWII 43-46 he was at guam, phillipenes and he was climbing surabachi when the picture was taken. I myself was enlisted in the USMC but failed out of meps due to being deaf in my right ear.

Alright so here we go. X pipes will quiet down your 400 and give it a different sound. But there is no performance gain from an X or H pipe at all unless you had it going into the X directly at the collector. But due to the fact of transmissions and such in the way you couldn't.

Now on the 351m/400 73-79 trucks when running a long tube header your either going to have to have it come under the crossmember or run it down the right side frame rail. The reason is because the collecter is only inches away from the tranny crossmember. Also the farther back the mufflers are in the exhaust system the quieter they will be due to the fact that the gases are cooling before the muffler. I run 2 1/4 inch pipe straight back to cherry bombs that are right in front of the rear axle then it continues out the back and exits at a 45 degree angle behind the rear tire.

Quiet at idle and cruise, and the biggest thing that I hate about loud exhaust is the drone. With my setup I have zero drone in the cab. But even though it's quiet at idle I still can here a nice deep rumble. Now when I hit the loud pedal she does open up and sounds good.

 

Thanks Mike. Semper Fi, to you and you granddad. I served in E Btry 2/12 1st Marine Division. I spent 3 tours in Iraq/Kuwait/Saudi Arabia. I also was in Guam, Okinawa, Korea, and Taiwan. 14 years total. I am now a Disabled Vet.

I was wondering about the x-pipe. One person said it would help, another person said my engine wasn't really big enough to need one.

I hated the expense, but I went ahead and purchased a set of Magnaflow Universals. I seen a video of them on Youtube. I was very impressed with how quiet they were. I really liked the Flowmaster 70 series mufflers, but, I saved about a $100, going with the Magnaflows.

Thanks for the info on the layout and location of the mufflers.