The brilliant engineers at GM used a tap off the power steering pump to energize the power brakes on larger vehicles. My SOB had that, and halfway home from buying it (about 20 miles) the P/S belt broke, and the last 8+ miles were without power steering or power brakes.

BUT WAIT! There's MORE! StaRV II has a 6.5L TD, with the same arrangement, except that while the SOB has separate belts (4 V-belts), the Barth has but one serpentine belt.

I can say from experience that if that belt breaks, one has:

1. No power steering (and Popeye wouldn't be pleased with humping the steering in such a case)
2. No power brakes
3. No engine cooling

On my way home from some star parties, the A/C compressor locked up, and terminated the belt in the Alabama hills. Fortunately, there was no traffic and a flat spot appeared in a few hundred yards to change the belt. Time: 1 hour - 55 minutes for the engine to cool (it never overheated) and 5 minutes to install a new belt.

So I take it that the pulley/clutch didn't lock up. Just the A/C pump? Had it of been just the pulley/clutch you would really of had a problem. If your new A/C pump doesn't come with a pulley/clutch spend the extra scratch to get a new pulley/clutch.

Although it would have been cheaper in the long run if it was just the pulley/clutch that failed you wouldn't have been able to drive it after replacing the belt you would have needed to tow it instead.

The clutch bearings are fine - the compressor shaft froze. It was low on freon, so I recharged it, but it failed anyway - it was due for replacement, as the shaft seal was leaking...I put a bit of oil in also, as that's what evidenced the leak, but it was already too far gone.

GM A/C compressors no longer use a keyed, threaded shaft - all are press-fit, so new compressors come with new clutches.