I have a 1999 ford f150 exhaust pipe and muffler

The auto store probably sells a big chisel and a 4 lb hammer? If your going to replace anyway, use a hack saw. In my younger days, I've cut many a tail pipe with a hack saw. So a new muffler and tail pipe will have new flanges? I can't see anything from here.

Starting from the front, coming off the exhaust manifold should have, 1. Exhaust pipe, 2. Catalytic converter, 3. Exhaust pipe, 4. Resonator, 5. Tail pipe. Also, there should be an Oxygen sensor somewhere around the catalytic converter.

New exhaust would be the best way to go. Maybe from the catalytic converter back. You can get muffler tape at your local parts store but it wouldnt be permanant nor will it pass inspection.

NEED TO TAKE VECHICLE TO MUFFLER SHOP LET THEM FIX RUST PIPE WITH A NEW PIPE.LET MUFFLER SHOP FIX BECAUSE THEY CAN WELD JOINT SEAL BOTH NEW EXHAUST PIPE AND NEW MUFFLER SO YOU WONT GET CARBON MONOXIDE POISON LET MUFFLER SHOP CHECK ALL THE EXHAUST SYSTEM BECAUSE THE WHOLE SYSTEM COULD BE RUSTED DROP DOWN WHILE DRIVING YOU PROBABLY NEED NEW EXHAUST PIPE HANGERS.

Flex pipe will work, or if it's a straight section of pipe you can buy a universal piece of exhaust tubing with flared ends, trim off the rusty ends on your original pipe with a hacksaw or Sawzall and slip in the new section. Clamp it with 2 muffler clamps and you're set. Total cost should be under $40.

You should use a hacksaw or sawzall. There is no way you are going to get it off by pulling a piece, by hand, that has been heat welded for 33 years of normal operation. Or just take it to a muffler shop.
Recently I bought my own muffler and catalytic converter and the muffler shop only charged me $60 to take the old ones out and put the new ones in.

the best way to find out what it is would be to have the 3 people in the car while gently pushing down on the car simulating a pot hole or bump and inspecting how the exhaust & shocks in that area where you hear the noise, are fitting. It sounds as if when the weight of the extra passengers is in the vehicle, probably your exhaust pipe/muffler/tailpipe is now closer than usual to another body part & when you hit bumps or pot holes, the extra force caused makes it bump or rub.

Generaly there should always be 1" of exhaust clearance from other parts. There could also be a problem with the shock/strut when the extra weight is placed on it. The noise should actually point you in the best direction & you should look for shiny spots on metal, pipes or things that appear to be capable of rubbing. Sometimes, the muffler /exhaust will lose one or more of the rubber O-rings it is supported by and that allows it to swing & bump making noise. Good luck.

Hi there
Just take it into the exhaust people and tell them that you need a new muffler ONLY. welded into the place of old one as all your problem is the BAFFEL plates have come loose and the welding is only spot welded and isent any good So a new muffler is ALL YOU WANT
Ron

Van will run but first get under and take off the centre muffler and then start if runs ok then replace exhaust system complete...
If still wont go you could have a blockage in the manifold but if the exhaust was buggard and bent it stopped the gasses coming out, like backing into a load of dirt and filling up the tail pipe with mud.
Or the catty converter is buggered.

Sounds like cat convertors are clogged.