Rear Roll Pan & Exhaust
 

I am building a 67 c10 fleetside short bed with a sbc 350 and 700 r4 transmission. I am having the exhaust system done without the cab or bed on the frame. I intend to use a roll pan on the rear and I want the exhaust to go thru it, not below it. At what height does the exhaust pipe need to be at for this in relation to the frame rail?

Re: Rear Roll Pan & Exhaust
 

It looks to me like the exhaust has to be roughly right in the middle of the frame. That is where the original bumper would mount and where your roll pan will mount on the bed. That is going to be a bit hard with that tank in the way. They are probably going to have to run the exhaust under the frame rails, then kick it up in the rear to exit out the back. You could run the exhaust in the frame rail, which would make it a lot easier to exit where you want it.

Re: Rear Roll Pan & Exhaust
 

I don't know which brand roll pan you're installing, but the pan on my truck doesn't attach to the frame.. It attaches directly to the bed.. Welded, not bolted.. Welds are metal finished and painted..

Seems to me you're going about it backwards. Is there a reason you're installing the exhaust before installing the bed and roll pan??

Re: Rear Roll Pan & Exhaust
 

I took a quick look at my truck. The bottom of my exhaust tube is a hair above the bottom of the frame rail, so the tube aligns with the bottom half of the frame rail. There`s a bed floor rail that hangs down on my 1970, so exhaust tube fitment is tight for straight alignment coming out the roll pan. I suggest you mount the bed first before installing exhaust. Or at least end the exhaust about 10" before the end of the frame and add the remaining end of the exhaust after the bed is installed.

Re: Rear Roll Pan & Exhaust
 

Have you considered side exits?

But if the bed will be off for the exhaust work, you're still gambling on the fit. Can you install the bed temporarily to take measurements relative to the ground?

Or, for through the roll pan, how about doing the tailpipes after the bed and roll pan are installed?

Re: Rear Roll Pan & Exhaust
 

Echoing other comments. If you want the best fitment, the bed & roll pan should be in place. That gives the exhaust installer reference points to land the exit to your satisfaction.
My '70 C10 roll pan was "notched" so the tips came through the bottom half. The tailpipes were parallel to and slightly below the center of the frame rail.

Re: Rear Roll Pan & Exhaust
 

This is the only pic I could find showing the Exhaust coming through the pan. Hopefully this helps

Re: Rear Roll Pan & Exhaust
 

Mine is side exit behind the rear tire ,shown here not connected to the headers and hanging down a bit.

One should be able to get the muffler shop to add a couple of bends so that the exhaust turns and runs out the back alongside the outside of the frame rail or just lower than the frame rail to have the exhaust exit though the roll pan, under the roll pan or through a notch in the pan. Unless you throw a fit and have them run out the back my go to muffler guy runs all pickup exhaust out this way in case the truck ever has a canopy or camper that someone might ride in.

Re: Rear Roll Pan & Exhaust
 

I have built a few full custom exhaust systems and this is one of the hardest parts to get right. You really need to find a way to mock up the roll pan in it's final position to get this right.

On the last one I did I had the rear bumper mocked up but it wasn't in the perfect position. When I went to final assembly, I wasn't happy how the exhaust pipes looked from the side with the bed and bumper on. Still need to redo them...