When I stripped my rust-free chassis, I removed all the brake lines.. I was surprised to see how clean everything was, no junk in the lines.. But, I have no idea when it was last serviced.. When I dismantled the rusted chassis, all kinds of nastiness came out of the brake system.. So.. while I have changed many master cyls the TROYPORT way, I always try to get back to the system and bleed it completely.. When doing my rebuild, I put everything back together with new calipers and wheel cyls, then opened up the brake lines and went about other tasks untill all the bleeders started to drip. Then I pulled out my trusty mityvac hand pump and sucked more fluid through, just to make sure there was nothing undesireable left in the system anywhere.. I then attached my large welch vacuum pump (the big bastard that I use on HVAC work, weighs about 100 pounds) and metered-up about 15 inches of vacuum to the booster, to simulate engine vacuum, had rock hard brakes, ready to go..
You should always flush the brake system - but the TROYPORT method will get you on the road in a pinch, but do it very carefully. It'* just my 2 cents afterall. Mike

If it has been 15 years, you will want to take a close look at any flexible hoses used in the system. They should be replaced if starting to show deep cracks. At that age, and with crummy old fluid, the insides of the hoses may have begun to delaminate, even if the outside layer looks okay. When they come apart internally, often the calipers will not fully release, causing lots of troubles.

jr'* momma didnt raise no fool

I will take a good look at the flex lines while I've got wheels off. Thanks for that idea. I don't believe I have anything sticking at this point, or refusing to flow back to the M/C, but I will take a peek and see how they look anyway.

I'm honestly not sure how old anything is on this car. I've owned it for about 6 months, and never actually met the previous owner. Long story. Needless to say, I have no records at all from it.

So yeah. I'll do my very best to bleed the whole thing out, and just use the other method(*) if necessary.

Thanks again all.

Well, one more thing maybe. I don't have parts yet. Anything I need to avoid or seek out as far as brands, etc., in a reman M/C? I see that Napa has one for either $36 or $54, apparently depending on the length. Doesn't mention a brand though. I don't guess it really matters much, but if anyone has had any horror stories with a particular brand of reman brake parts, that would be good to know now, rather than later.

Measure yours first. It'* either 8" or 10".

Surprisingly, both my cars use different lengths.

Yeah, I noticed that there are different lengths on the Napa site. Quite the price difference, too. Can't imagine why.

Mine measures 6 7/8" from booster to the end. That'* closer to the 6.5" vs. the 8" that Napa offers. Ah, good. It'* the cheaper one.

If you take into account the distance taken up as the MC enters the recess in the booster, and the thickness of the mounting flange, you have an 8" master.

Well, that was factoring in the mounting flange, but not anything poking inside of the booster. I guess that a length measurement is rather dependent on what they expect me to actually measure.

So with that in mind, and mine measuring 6 7/8" from the face of the booster to the tip of the M/C, is it going to be the shorter of the two (6.5" according to Napa), or the longer (8" according to Napa)? I suppose I could actually go to a parts store and have them set a couple on the counter for me, but this couch is rather comfy... I'll probably end up getting one ordered through my brother, so I want to make sure we get the right one.

The current unit does have a GM barcode sticker on the line side, so it'* not some odd aftermarket freak.