The wattage on your new stereo is probably greater,and cleaner than the factory amp.I don't know if the inputs on the amp could take 50 watts a channel either.I bypassed my amp,and am running a 50x4 stereo,and it sounds much better than stock.Hope that helps.
I went to a car audio store and they sold me a wiring harness for my new CD player and it came with the Amp by-pass adapter for the "Ford Premium Sound". The minor problem was one of the ends was wrong on the by-pass harness. The male end of the factory harness that came from the factory radio and pluged into the amp, was different than the female end of the bypass. The other end of the by-pass harness that pluged into the speaker harness was just fine. So I undid the tabs that holds the factory wiring in behind the dash. Pulled all of it out (super easy to do, it is less than 18 inches of wire) I then cut the two miss matched ends off, and followed the color coded wiring diagram and made my own by-pass with the orginal Ford Premium Sound amp harness (which you do not need after the radio swap) and the by-pass that comes from the car audio store. I basicly took the ford harness and the by-pass harness and made them into one harness.
It took me about an hour to make the two harnesses into one harness. From there I ran the wires back behind the dash where they were suposed to go and pluged everything in. "Sound" is all better.
So to answer your question... I made a harness. It only took me an extra hour of time over the standard insert of an after market CD install. Hopefully you can buy the correct by-pass. I did find out that the Bronco Eddie Bauer Premium Sound amp is slightly different than the other ford amps. This is why my after market "92-97 Ford Truck Premium Sound" by-pass harness did not fit right in.
I have worked for 2 of the big name stores and a few other ones for over 8 years doing car audio and electrical. coming from someone that did this for a living i will tell you that only MAYBE 5% of the time did we keep a factory amp. even most cheap-o radios put out more power than the older factory amps. get rid of them, they make great door stops... thats about it ;o)
aftermarket stereos are always going to be better than stock.. but one thing that hardly anyone ever notices is MAX POWER AND CONSTANT POWER your radio thats 50W x 4 is NEVER going to be that high, basically if it gets struck by lightning it will give all 4 speakers 50 watts, your probably getting 17 - 22 watts of continuous power depending on the brand of stereo you have. always find out the RMS or Continuous power of a stereo to know how much power it is actually puting out, SAME THING WITH ALLL audio equipment, subs, speakers, amps, etc. but after market is pretty much always better than stock in most cases. and the factory will push out about as much as an aftermarket stereo but still not as good quality of sound.
The Amp on my 1995 Eddie Bauer Bronco was in between the firewall and the back of the instrument cluster right above the gas pedel.
The easiest way to find it is to lay on your back infront of the driver seat. Place your head by the gas pedel and look up under the dash. The Amp will be right up against the firewall, and it will be high up like it is right behind the instrument cluster. I have big hands so it was kinda hard for me to get to.
Mine had a big plug that goes to all the speakers, and a small plug that came from the back of the radio. So the small plug is signal "in", and the big plug is signal "out".
I hope this helps. I did a search and found a guy who had removed his whole dash to get at his radio. It is the very last thing before you hit the firewall. As far as I know there is no good or easy way to remove the Ford Amp from it's hiding place.