My OE rubber bushings lasted less than six years and fell out when I removed the trackbar. Same for many early owners, which is what got the whole polyurethane thing started in the first place.
My poly bushings lasted 30 years and were as good as new the last time they got checked.
The first two sets of poly uppers got a little loosey goosey after only a couple of years each, but lubing the next set better, then changing to an adjustable trackbar to correct the angle of the eye after a lift made all the difference. No bushing, rubber or poly takes kindly to being put into a bind in it's neutral position.
Apparently installation procedures can make a difference.
I've been hearing you take all people to task, very unreasonably I feel, who try to sell things to Bronco owners. Not sure how many times you've felt you've been screwed over by going with the recommendation of a sales person, but I sell poly because I believe in them. Not because I make more money on them, or can't get rubber ones to sell you in their place.
In the case of trackbar bushings, the recommendation for poly has nothing to do with price, profit, or even firmness. Rubber can do a passable job of most of those too.
But most of us experience long and happy lives with our poly bushings, find them easy to work with and like the product. Even though rubber should have the advantage in NVH reduction, there's no apparent difference when in use for most users.
The fact that some of us have good luck with a product and like it better than another one that you happen to prefer does not always need to send up red flags for you to think they're recommending something based just on the profit they can make from selling the to you.
If someone wanted rubber I'd say fine to that too. Does not matter to me what I am able to supply a customer that fits their needs. Just as long as they're happy with the results.
And in most cases rubber would not fit that bill at all. After all, most of us that do most of our own work don't have the equipment needed to install stock style vulcanized rubber cartridges into a trackbar eye. But poly can be done quickly and easily by hand in most cases.
We'd have to take rubber trackbar bushings to a specialty machine shop with a heavy duty press and an experienced operator. The '77 looks to be a different beast that should press in much easier than the '75 and prior ones do. Those earlier ones are a bear. I've heard members here say they've done them without too much trouble, but more often than not they don't give in easily. I could not get the set I bought from Ford in to save my life. Poly on the other hand saved my bacon.
Even two different machine shops and the dealer could not install a set for me once. Their presses and/or procedures were just not good enough. Or they were the wrong part. So going poly was a no-brainer rescue for me.
A poly set will install in 30 seconds without tools other than strong hands or a heavy foot. A hammer or vise are not necessary, but make shorter work of it if you feel the need. And in most cases, last as long as the person owns the vehicle.
For many of us then, poly still rules.
Your results may vary of course.
Paul