87 RAM Vibrates violently when breaking

Hello, I have an 87 Ram D250, 5.9L V8 truck, it's my fixer upper project to learn more about cars. I just fixed a flat on the front passenger side. Since then, whenever I go over 35mph and apply the breaks to
slow down/stop, the car vibrates violently(and I'm not using that term lightly). It feels like the whole truck is going to fall apart. Any ideas or help? Greatly appreciate it. What I have done so far: I made sure all the lug nuts are tight and secure; made sure the tire is seated right; the tire is the right size and everything. My guesses: with some of these older trucks, you have to install the
tire at very specific way (i.e. if you took the tire off with the valve
stem at 6 O'clock, you have to put it back that way). Second guess, perhaps the rotors are warped and I need to re-surface them.
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Might be warped rotors.

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i have to agree ,either warped or grooved rotors
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