To both questions, yes. The LED had the same part number as you specified in your diagram, and the longer connector was the positive according to the package. I was very careful about that.
I think I hooked it up backwards the first time I tried it. Would that have blown out the LED?? Backwards in the socket I mean.

Possibly

try it both ways on the battery and if it does not light either way, it is done..........w/o the switch... b/c you could have a bad sw .

You can do the same test , but use the odd lead for the battery neg, and that will eliminate the switch from the test circuit.

Doesn't light up when the black and red are reversed either.... I tested off the odd lead as well... Nada.... I'll have to get a new LED the next time I'm in the city....
Dad just bought an OBD2 scanner. Would that work to check from the port under the dash by any chance??

I read the codes with the obd2 code reader. It gave me back three codes. They are:
P0306 I think that was from before I replaced the spark plugs and connectors.
P0193
P1633

I ran a test again with the OBD2 scanner after driving about 50 miles stopping and starting. 3 engine starts, ran the car up to about 90 miles an hour, hard acceleration, regular acceleration.... No new codes either in pending or in stored.... Should I figure that the problem is fixed for now??

I think you need to check the 38 pin connector too to confidently say that there are no fault codes. OBDII just isn't as broad as OBDI.

Guess I'll need to make a new scanning tool. It appears I have a bad LED then...

Got a working code reader today. Didn't get a single blink from pin 19. ONly codes I got were pin 6 code 17, and pin 23 code 15....
Don't know what that means...

I know that I have read a lot of posts where people have tried cleaning the Mass Air Sensor with no luck. The last time I had a Mass Air code on my '96 C280, I did the following based on information from a friend that used to manufacture the Mass Air Sensor. First, used the CRC cleaner, then used contact cleaner on the connector, finally di-electric grease on the connection. It has been over nine months since the CEL came on.