Search for clutch pedal bracket and you should find a lot of info on this. It is not an uncommon problem. My old 79 did it to me while I was on vacation and I had to tear it apart in a hotel parking lot to get it welded back together.
If I remember right there are four bolts to the firewall and two at the other end hooking it to the dash. I found it easiest to take out through the hole for the gauge cluster. You also need to remove the brake pedal completely and anything else you can get out of the way. Get the gauges out (3 wingnuts hold it in, two on the left end one on the right plug the speedo cable and wiring harness) and start looking at what you are up against.
I have not seen a good solution to fixing it in place but I suppose if you are creative you might figure something else out. My current 79 project this is on the list of things to fix before it breaks. With a little extra metal and some welding it will last much longer than stock.
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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)
MEPR: Man, my 4x4 makes all other LUVs look good
