Just to add my .02 to what already has been posted:
1) I hear about 8-, 9-, 10-, 12-bolt rears, but I have no idea what those actually are. Can anyone explain what they are, and the differences?
Rears are referred to in two ways, the bolts on the ring gear, or the diameter of the ring gear. Normally GMs are by bolt, Ford's are by diameter. We'll leave the Dodges out of this, other then the big gun the Dana 60!
Basically, the larger the gear, the more material it has and there is more room in the differential casing for larger stronger supporting parts such as the posi, axles, etc. The bigger you go, the more weight you add to the car, as well as the HP needed to turn the parts. cost can also go up!
A 3rd or 4th gen come with a "10 bolt" rear, this late model 10 bolt came out in the late 70s and contains 7.5" ring gear (when a 350 engine made under 200HP). Pre 1977 "10 bolts" had 8.2" ring gears. and there were HD 10 bolts with 8.5" gears as well. The "12 bolt" has 8.9" gears. Ford uses a 8.8" ring, and the HD unit has 9" gears, (so the name 9" rear). The Dana 60 has 9.75" ring gear.
2) Is there any difference between a Limited Slip Differential, and Posi-traction?
There is no difference in what a LSD, Posi, suregrip ect does, it applies power to both rear wheels. Differentials basically come in 3 styles:
A) Single or Open rear - Only applies power to one wheel (typically the passenger side). Uses less of the engine's HP to turn. Good for low power engines, better fuel economy. Not good if that one wheel looses traction!
B) Posi, LSD - Uses a mechanical clutch within the rear to allow power to be applied to both wheels when going in a straight line. If one wheel was to loose traction the other tire is still applied the same amount of power. When the car turns, the pressure applied releases the clutch. (outward wheel travels a further distance then the inner wheel). Vendors set this release point and for special applications set the release point higher. (bit off subject, but this is why if your spare tire is not as tall you want it to swap tires to put it on the front. long distance driving will cause the posi's clutch to burn up!)
C) Locker or Spool - A solid or constant connection to apply power to both wheels. This is very useful for straight line racing, pulling or towing. Lockers/spools are not optimum for street cars, turning results in a tire needing to skip or skid during a turn, making them unsafe and place allot of stress on the other parts of the drive train such as the axles and rear gears.
3) What is the most effective after-market security system I could purchase? I was thinking some kind of kill-switch to the battery would work, but I'd like others opinions on which works the best.
Most type of visible security is useful, (blinking light on the dash, window sticker can save you a broken window), a kill switch is always good, something you can hide yet still access easily. One idea is to kill the signal to the fuel pump, should a thief get the car he can only travel a short distance, keeping the car from getting stolen, while getting him a few blocks away from you. I’ve seen people build them from their cigarette lighter, so they simply push it to complete the circuit.
An aftermarket system that has sound and motion detection will give you the most protection.
But the bottom line is that if they want your car, they’ll get it!
4) I'm looking for a shift knob for a manual transmission. Gardocki was kind enough to give me some websites like jegs and summitracing, but their selection is a bit limited, specifically in the L-shaped range (tall or short). Any suggestions?
What are you looking for?
http://www.flameball.com/HomePage.htm
http://www.koolknobs.com/
5) I would like to "rust-proof" the underbody of my car. Does anyone have details on this procedure; is it easy enough for a do-it-yourself project, or should I have an auto body specialist take care of it?
I use Eastwood’s products, and I’ve very happy with the results. I basically clean up the frame and underbody and applied their frame paint. I did my 99 GMC and after 9 years and almost 200,000 miles it still looked good. The new truck will be getting the same treatment soon!
6) In general, where is the best place (online and off) to get parts for my F-body; aftermarket or "original replacement parts"?
No one vendor has the best price on everything. You really need to shop for what you want. For aftermarket parts, often our site sponsors will give you some type of deal.
For original parts, gmpartsdirect.com is a good place if you know the part number.
7) How much wood would a woodchuck chuck if a woodchuck could chuck wood?
That really depends on the size of the woodchuck.
8) What would be the best performance increase, in terms of cost-to-power ratios (the cheapest method for HP or Torque boost)? This can be specifically for my 5.0 HO TBI manual, or just in general.
*edit* The cheapest method besides putting stickers, decals, and coffee cans on the vehicle--as well as these methods work for hondas and other rice, I'm not much of a fan.
The engine is a pump, it needs to breath. The more efficiently you can move air the better the performance, so start with the intake and exhaust. Headers are probably the best bang-for-the-buck mod. If your talking performance and not just HP, gears probably are about equal to headers.