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Discussion Starter #1
I pulled off my original GM pan from my THM400 and it's a bit warped and was leaking pretty good.

Advance Auto has, what the guy working there said was a cheap (in all senses of the word), a Mr Gasket chromed replacment pan for $40. He said he wouldn't recommend it as it's a chinese piece of other metal than steel or aluminum. Also the chrome is much more susceptible to leaking from what he said.

I've looked at Summit and they have a couple, some for about$60 and some for about $115. They all say they are "deep" and need about 2 more quarts than stock, I don't really want that thing hanging down further than it is.

Any suggestions on these or somewhere else to get a decent pan?

Jeff
 

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Discussion Starter #2
Derale th-400

I actually found a Derale th-400 pan on CL located within 50 minutes of me.

Never heard of Derale, are they any good?
 

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I have the deep finned aluminum one from Summit. It has a drain plug and does not hang as low as the oil pan. The 2 extra quarts help in cooling. (I'm also running a 2800 stall converter)
 

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Discussion Starter #4
My local AutoZone can get me this one: Spectre Chrome Turbo 400 Transmission Pan for $41.

It's chromed but shouldn't I be able to scrape that off to get to the steel underneath?

I've also heard several different theories whether or not I should use any kind of gasket sealer on my rubber gasket I got from NAPA. Some say no other yes. :smack
 

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Discussion Starter #5
I have the deep finned aluminum one from Summit. It has a drain plug and does not hang as low as the oil pan. The 2 extra quarts help in cooling. (I'm also running a 2800 stall converter)
No idea what stall converter mine has as the trans isn't original to the car.

But the oil pan bottom is dead center between the front tires, whereas the trans pan is more in the middle of the car and more susceptible to scrapes if it's hanging lower than stock on things like speed bumps. There were already 1 or 2 scrapes on the stock, steel pan.
 

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Trans Pan

On my TH400 I have what I believe is called the "truck pan".....this is the slighty deeper one that was stock on trucks equipped with TH400's. It holds about one quart more than the car trans and is about 1/2" deeper. You have to use the slightly deeper truck oil pick-up with it.

The trans shop (Rosslers) suggested this pan when they rebuilt my trans. You may have to search, but these pans are still around.
 

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Discussion Starter #7
On my TH400 I have what I believe is called the "truck pan".....this is the slighty deeper one that was stock on trucks equipped with TH400's. It holds about one quart more than the car trans and is about 1/2" deeper. You have to use the slightly deeper truck oil pick-up with it.

The trans shop (Rosslers) suggested this pan when they rebuilt my trans. You may have to search, but these pans are still around.
I actually found a shop locally, Kennedy Transmission, that had both the stock one and the truck one, both used but were in way better shape than mine. The truck one was definitely heavier and looked like it had a better seal around the edges than the stock one. However he said you have to use an adapter for the pickup and also a spacer for the filter. I decided to not go with the truck one as it's a good 1" deeper than stock. I never looked at how low the pan hangs when it was on there. When I go to put it back on, if I think 1" isn't a big deal I'll definitely go back and trade for the truck one.

He also said the rubber gaskets are junk and to only use the cork ones on this pan. He had a cork one so I won't be using the rubber one I found at NAPA.

I stopped at my local Chev dealer to see if (primarily for laughs) to see if he could order me a new one. He said the part had been replaced with one that went with a Cadillac. It wasn't a great picture as it was small but it looked to be the deep version. Was about $90, but I passed as I'll try these other two used ones first.
 

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I have the deep finned aluminum one from Summit. It has a drain plug and does not hang as low as the oil pan. The 2 extra quarts help in cooling. (I'm also running a 2800 stall converter)
Do you have to run a different pick-up with this pan? I have one to put on my th400 but was holding off until I found out if I needed to change the pick-up as well
 

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Discussion Starter #9
seals

Are there any other seals that I can easily replace right now that I have the thing all apart and fluid emptied?

I've already done the rear seal, the front one I won't be able to do. But what about the shift linkage and the speedometer? I assume both of those opening are below the fluid and require a seal. However, I think the shift linkage requires a special tool to remove it.
 

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Chrome won't get you home, but if you use some rough sandpaper and scuff the gasket rails LENGTHWISE you'll improve your chances of it not leaking. The chrome is so slick the gasket can't "bite" and can ooze out and leak.

A deeper pan is not a bad idea, but you also need a longer pickup tube and get the filter lower into the pan. Be sure and use 2 o-rings on the upper end of the pickup tube.

You may have already thought of this, but one of your local trans rebuild shops might be a good place to source a new pan.
 

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I actually found a Derale th-400 pan on CL located within 50 minutes of me.

Never heard of Derale, are they any good?
They are a well built pan, thick metal flanges, deeper for increased capacity, provision for temp sending unit, drain plug and has the cooling tubes in the bottom.
 
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