john in KY

Could be. Thinking the very early Legacys used a 3.90 ratio and then changed to the 4.11. Edit: Got that backwards. Early Legacys came with the 4.11 and then switched to the 3.90. http://bbs.legacycentral.org/viewtopic.php?t=32148

Electrical a good guess what is causing that clunk? Anyway you can check for line pressure when the problem occurs? Thinking maybe a TC or pump problem. Not a transmission guy but thinking there is a port somewhere where a pressure gauge can be attached.

Could be a burnt exhaust valve. #4 cylinder has a history of this for some reason.

Just for jollies, check all the lug nuts for tightness. U-joints last a long time before failing. The only u-joint failure I had happened right at 300K miles.

Replace the oil pressure sensor while at it.

Have the fuel pressure tested and check for a ruptured fuel pressure regulator.

Don't know where you checked for spark but still won't fire even with starting fluid has me thinking the distributor timing is way off or the spark at the spark plug electrode isn't enough to ignite the fuel.

Don't know exactly what it is called but "power transistor" comes to mind. Never hear of one failing but as for the no-start problem, the entire coil bracket has to be grounded. The power transistor grounds to the coil bracket and the bracket to the rest of the car. No ground=no start. Check for a broken timing belt before anything else. Does the distributor rotor turn when the engine is cranked?

I'm thinking driveshaft.

Could be a fuel pump failure but my first guess is the timing belt.

Your vibration comments got me to thinking you probably have the driveshaft failing along with your other problems. When it fails it likes to take out the back of the transmission along the way.

Not difficult, so I have been told but think about why that part cracked. My bet is the driveshaft front u-joint failed.

According to Rockauto, same axles.

One way to test the fuel pump is to pull the fuel line at the fuel filter. Messy but effective. Wonder why no one has mentioned a broken timing belt?

Check the cat convertor after a drive. If cheery red than the engine is running very rich.

Pull the spark plugs and look for black specks on the white porcelain. If the porcelain is pure white but speckled with spots, go with a colder plug.

If your 91 is anything like a 95, power originates at one of the slow burn fuses in the underwood fuse pane. Thinking #1. Then down to a relay under the instrument panel, just behind that kick panel under the steering wheel. This relay services both the sunroof and the power windows. Since you didn't mention the windows not working, circuit to the under dash relay is good. Power then flows up to the overhead console. The switch in the overhead may be bad. That switch can be unplugged. Has a very short harness. But my guess is the sunroof has a broken cable or stripped gear or whatever is used to make it move. I'll try to find and paste a wiring diagram someone gave me when I had a sunroof problem. Fuse 15 also in the circuit. Found that diagram but would not paste.

Should be a tag over by the starter hole that can be decoded. As far as I know, the SVX only used a 3.54 differential. No other model Subaru used this ratio.

Well if it is an import, the steering wheel is on the wrong side.

CV boot tore. That "fluid" is axle grease. Have the boot replaced and you'll be good to go.

Don't know much about alternators but thinking they require a "turn on" voltage provided from the ignition. Should be easy to check with a test light. Also wonder if the problem could be just a fuse.

Disconnect the harness at one of the injectors, use a test light and see if the injector is receiving power when the engine is cranked. If the test light pulses, than the problem is a grounding problem. Are you sure the fuel pump is working?

Why not just pull it and note what now doesn't work?

In my experience, overheating and the heater blowing cold has always been either low coolant (air block) or a failing water pump. Low coolant 95 times out of 100.

First verify the wheels are indeed 15" and not metric. The tire size will give you the answer.