Yah, i think your right. i took a good shot at doing it myself, but at this point i may need a pro. other than changing the radiator which is easy, i don’t trust myself to take the plug out. it runs fine now, im thinking driving it to the mechanic is a better idea. ill just replace the radiator first to save some cash. if tranny fluid is getting inside, better to have it at the mechanic as well. there is just a HINT of oily sheen on top of the water, does radiator fluid do that?
I will thanks. i love that there is a place like this a person can ask questions. i have a buddy who was an expert at old schools who passed recently and its just hard to get good info without paying an arm and a leg. have had shops decline to work on this car in the past because of its age. Its sweet though. ill post a pic
If you replace a radiator that doesn’t need replacing, you’re not saving cash.
Tester
It doesn’t take much trans fluid to discolor the coolant.
I have a hand vacuum pump w/gauge. Disconnect trans lines, plug one end of cooler and pull vacuum on the other. Watch gauge for leakage.
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That is awesome! thank you. This is what it looked like before i put in the radiator flush liquid which turned it a darker blackish color.
there was a dash more red to it in the beginning. its kinda faded. i had to stir it up for this photo.
Removing a rounded off engine block drain plug using a Bolt-Off socket.
Tester
Heh heh. I had a 67 Buick wagon that looked a lot like that. Yeah great place to ask questions but just remember the answers may vary. Some of us are less qualified than others but hopefully good advice comes through. You used to be able to take a radiator to a shop and they would clean, rod, and repair them for $50. Dont think many do that now and last radiator I bought was a little north of $100.
thank you kindly! I think i can filter the good advice out. 
I really appreciate it!
A little pricier than what I thought.
You haven’t bought a radiator in a while, have you Bing?
ROCKAUTO.
Tester
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Nice looking Impala, low and slow and rocking some Vogues… lol
Or another adventure would be to try to force the block plug out and if you damage it, then it gives you a good excuse for a 383 small block stroker… Or LS swap… lol… Just saying 
Adjusted for inflation $50 in 1970 is equal to $395 today. Who would want to pay nearly $400 to clean a radiator? Things cost more back then.
I’m going to concur with @Tester on this, but if you can’t get the block drain out, it may be easier to pry out one or more “freeze” plugs. There should be two or three on each side. They are not too expensive to replace either, but I haven’t bought on in 40+ years so I don’t know what they cost today.
The freeze plugs give you a nice big hole to flush out the sediment.
BTW, really old coolant turns a muddy brown. It looks like you dredged it up from a mud puddle. It even has the texture of mud.
But, about 10 years ago, I bought a used handicap van (Chevy C30) for my sister in law to take my father in law around. This was a van that people bought, kept for a year or two and then sold when the loved one died. I’m not sure how many times it had changed hands but it was clear that no one did any maintenance on it.
The coolant in it was a thick muddy brown. I drained the radiator, the block and both heater cores. I never flushed it, just put all the heater hoses back on, replaced the block drains (they did not stick on me, there is a trick for these) and closed the replaced the radiator valve (it broke when I opened it) and then just refilled at about a 2:1 coolant/ distilled water mix. That was 3 gallons of concentrate and 1.5 gallons of distilled water. It cleared right up.
The trick is to first turn the drain plug in a fraction of a turn, then back, then in and back. Rust builds up on the threads exposed to the water jacket. By alternating back and forth, you can work the rust off. Start in first to get a running start when you start out.
Don’t get me started on the oil change for that beast.
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- 4 on floor. in a wagon? how awesome would that be?
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lol. its due for a lot of maintenance. 70k original miles. im taking it in for an overhaul here shortly. i was just trying to save a little money. ive done this before on a lot of cars, ive just never seen anything like this. your advice on the drain plug is good. slow and steady wins the race.