Hooked up to a Snap-On scanner today due to some noises that are not exactly nice.
In Park I lightly revved the engine to about 1200 rpm.
After about 1 second the Knock Retard jumped from 0* to 15*.
Advanced Timing went from 35* to 20*.
I let off and the KR dropped to 0* and the advanced timing went to 17*.
I then revved it to 1500 rpm and the timing jumped to 35* for a second and the Knock Retard showed 23* of KR.

Yup, that definitely is a main or rod bearing. :(
In a way I'm glad it'* not my car, but I'm sad to say it is the 1997 Park Avenue I bought and traded to my dad who sold it to my uncle and aunt.
Luckily I found a motor out of a 2002 Lesabre with 49k miles that is 130 miles away for $250 and a call to a mechanic friend got a install quote of $250 + any coolant, oil, filters, etc... which would bring the total cost up to around $575-600 to get them back on the road so they can visit their daughter in Manitoba in a couple weeks.

Wow that'* nasty.......You live in the best area though....an engine like that around here generally would go for $600+ unless it came from a burn car.

are you positive its not false KR from whatever this noise is?

If it'* a rod knocking, it'* loud enough it would more than likely wig out the Knock Sensor...

You and Seth should get married. Bad luck in MN land lately.

The mechanic and I were definitely positive the rattle was in the bottom end. Stethescope on the water pump, transmission, valve covers, LIM, alternator, Power Steering pump sounded like fresh bearings in good oil..... quiet and smooth.
On the Intake manifold'* (went from passenger side runner to runner nearest the TB) and the noise was more audible the closer we went to the TB.
We pulled the plug wires and found the 1/4 coil to have very rusty connectors so we cleaned those and the spark plug wire connections and that didn't change anything. I pulled the 1 and 4 plugs and they look good.

He said false KR wouldn't be that high if it was coming from outside of the block unless it was some really heavy knocking on the block, which would be audible to the ear, especially with the hood open and someone over the engine like we were.

Hey, I stopped back in with the SSEi and we went for a ride with the Snap-on hooked up. NO KR BABY!!!!! 17* advanced timing too. I'm thinking before I put the 3.5" on I may see how far I can advance the timing in 80* weather with the stock pulley and see what that net'* me. Might even swing for a timing **** in my SSEi so when I go to the track with Toluene or race gas and a aeroforce (I've decided that'* where I spend money next on my car) I may even be able to run up to 20* advance on race gas.