Well here is a summary of the modifications I had to do on the 00460754 upper bracket.
First, I cut a cardboard template of the bracket so I could hack it to death without worry. I ended up cutting the template about 1 1/2" below the bottom of the bolt slot. I attached the remainder of my cardboard bracket to the short bottom bracket bolt. Then I folded it over until it mated up with the slotted portion. I clamped the two together with a spring clamp. Then I was able to slide the alternator through it's range of motion. I set it up so that when the belt was in the loosest position there was about 1/8" clearance between the back of the alternator and my valve cover. Then I moved it to the tight position being watchful of binding.
A few things to watch for are, the lugs that hold the front and rear portion of the alternator together. Also be sure the bracket doesn't bind up on the case in mid-stroke. When the alternator is in the loose position, the bracket will stick up above the alternator. It looks odd, but its normal since the radius of the bracket is less than the radius of the alternator. If you position the bracket in the loose position so it looks right, it will bind up when you try to tighten it.
Once I had everything aligned, I cut the bracket. I ended up disposing of about 4" of the mid section. On the long piece I cut it about 1/4" longer than my template. Also beware that the cut will be angled so make sure you account for that or else you have to stretch [img]graemlins/clonk.gif[/img] the bracket.
The long part of the bracket will need to have a slight bend in it to line up squarely with the back side of the lug on the alternator. I bent mine about the thickess of the bracket being careful not to bend it too close to the lower mounting point. If you bend it too close to the lower mount it will bind up on the lower bracket when you tighten the belt.
Put the two piece of the bracket in place. They should overlap. You can use vice-grips to clamp them together for a test fitting. Move it through the range of motion and adjust as needed. Watch those case lugs in particular. Once it is all the way you want it, scratch a mark on the straight piece to match the cut on the curved piece. Then make the final cut (should be about 1/4" of material) on the straight piece. Bevel the edges of both parts and tack weld them together. Give it a final fitting. When it is all good it's time to weld.
Be sure to leave a gap between the metal of 1/16" or so for good penetration. I used one of those 80 Amp Lincoln welders. I cranked it up high (about D 5) and layed in a bead on both sides. I layed two more beads on each side beside the first beads to fill the voids. I then spotted a little metal on the edges of the seam to fill those in.
I ground the welds down to the level of the bracket. I used a flap-disk on my right angle grinder to smooth it down good. A touchup with a file and a wire wheel and you couldn't tell where the seam was. All it needs now is a coat of paint.
I didn't say this earlier, but that bracket was $8. Notice that the part number I listed isn't exactly the same as the number listed in the tech reference. The part number in the tech reference
was listed as a pulley on GM Parts Direct's
web site. I still intend to verify with my local dealer, but the part number listed here is what I used.