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Discussion Starter · #1 ·
I'm putting my 87 Chevy SWB back together with the parts I have on hand. I have a T350 trans going back into this truck, but I cant remember which torque converter went in it. I ditched a T400 from a parts truck and both converters say 350 on them (hand written with magic marker) I'm sure the T400 was stock, but rumour had it the T350 was originally bolted up to a strong engine once. Is there any way I can tell if one of these converters was a performance aftermarket unit by the markings? The bolting flanges/bosses are different. The one on the left came from the T350...I think.
 

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Gearhead forever said:
I'm putting my 87 Chevy SWB back together with the parts I have on hand. I have a T350 trans going back into this truck, but I cant remember which torque converter went in it. I ditched a T400 from a parts truck and both converters say 350 on them (hand written with magic marker) I'm sure the T400 was stock, but rumour had it the T350 was originally bolted up to a strong engine once. Is there any way I can tell if one of these converters was a performance aftermarket unit by the markings? The bolting flanges/bosses are different. The one on the left came from the T350...I think.
the converter on the right is your chevy 350 converter. takes 3/8 x 24 thread nuts and bolts about 1/2 thread length on the bolt.
if your actually considering using that converter, i suggest you use some scotch brite pads to get the rust off the hub
 

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every time i tell someone that the th350 ones are the ones with the hole tabs like on the right, i get argued with by noobs who think they know, but actually dont.


haha

but regardless, the 350 and 400 ones do interchange


good luck
 

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I will point out the Buick , Olds , Pontiac style t-350 used a threaded pad and bolt design as the converter on the left side of the photo posted in the original message.
 

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The one on the right looks like a normal non-lockup converter from a TH350 behind a Chevy motor and was occasionally found with TH400s.

The one on the left looks like it MIGHT be a LOCKUP converter from a TH350C or maybe TH700-R4, TH200-R4, or TH200C.

Check the spline counts where the input fits in the converter. That would probably tell you what it fits.
 

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Discussion Starter · #7 ·
Thanks

Thanks everyone. The replies made me dig deeper, and I have found I actualy have a TH350c. I understand this means that it is a lockup TC, and that this trans is more than likely not the original out of this truck. I`m wondering if the comment that it might be a BOP, means anything as far as running it with a SBC.

Can someone give me some insight as to what a lockup trans means...I presume its still a 3 speed (non OD) Is there any benefit to this over a TH350 trans
 

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Gearhead forever said:
Thanks everyone. The replies made me dig deeper, and I have found I actually have a TH350c. I understand this means that it is a lockup TC, and that this trans is more than likely not the original out of this truck. I`m wondering if the comment that it might be a BOP, means anything as far as running it with a SBC.

Can someone give me some insight as to what a lockup trans means...I presume its still a 3 speed (non OD) Is there any benefit to this over a TH350 trans
A Lockup Trans has a clutch inside the Torque Converter that is activated by an electrical solenoid and Hydraulically. All torque converters slip some, it depends on the stall rating as to how much. The Lockup clutch eliminates this and reduces the engine rpm 150-300rpm providing slightly better MPG.
Some Lockup Info here, applies to TH350C converters also.>> http://www.phoenixtrans.com/html/lockuplowdown.pdf
There's a Pic of a TH350C converter here on Pg.12>> http://www.transparts.ru/pdf/tc_gm_03_web.pdf
 

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The one on the right is for a 350TH bolted to an internally balanced SBC. (i.e. not a small block 400) From the picture, it appears to be a stock stall unit but the only way to really know is to open it up. If stock is all you want, you can take it to a converter shop and trade for a fresh stock unit. If you are wanting a stall change, that one will have to be opened and adjusted. Unless you are going to drag race or have put a bigger cam in the engine, stock stall is all you need. In any case, the one you have there will need a new hub, at least. If you use that rusty thing your pump seal will last about a minute. If you need validation on what I am telling you, I own a converter shop!!! Sarge
 

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Gearhead forever said:
Thanks everyone. The replies made me dig deeper, and I have found I actualy have a TH350c. I understand this means that it is a lockup TC, and that this trans is more than likely not the original out of this truck. I`m wondering if the comment that it might be a BOP, means anything as far as running it with a SBC.

Can someone give me some insight as to what a lockup trans means...I presume its still a 3 speed (non OD) Is there any benefit to this over a TH350 trans
The TH350C transmission was discontinued by GM years BEFORE 1987, so there is no way that it is stock in your truck.

The converter on the right will NOT work in a TH350C.

BOP = Buick Oldsmobile Pontiac and refers to the bolt pattern where the transmission bolts to the block. BOP transmissions have a "Rabbit Ear" bell while Chevy V8 transmissions have a pointed bell and they do not interchange.
 

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Discussion Starter · #11 ·
mmerlinn said:
The TH350C transmission was discontinued by GM years BEFORE 1987, so there is no way that it is stock in your truck.

The converter on the right will NOT work in a TH350C.
Chevy V8 transmissions have a pointed bell and they do not interchange.
Thanks mmerlinn, your comment made me double check the validity of the year. I've found that you are right...the truck is an 87 and the last year this trans was in these trucks was 86. The bellhousing appears to be pointed so I'm ok there. I have no clue whether this trans is any good even. It was in the truck (no motor) when I bought it. The truck was being scrapped...so I'm not holding my breath. Sure looks rough. (see pics)

I was going to hook it up and see. If its junk and I have to drop some coin its just as well...I ultimately want to swap in a 4 or 5 speed manual or a TH700r4. Basically looking to get this thing running and driving with what I have and then upgrade every winter.

Thanks Sarge, I'm ditching that rusty one...must have been from the TH400.

Thanks again guys, awesome support here!
 

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Gearhead forever said:
Thanks mmerlinn, your comment made me double check the validity of the year. I've found that you are right...the truck is an 87 and the last year this trans was in these trucks was 86. The bellhousing appears to be pointed so I'm ok there. I have no clue whether this trans is any good even. It was in the truck (no motor) when I bought it. The truck was being scrapped...so I'm not holding my breath. Sure looks rough. (see pics)
Thanks Sarge, I'm ditching that rusty one...must have been from the TH400.
the rusted converter is a 350 converter, just a non lockup. the trans your showing is a lockup 350. youll notice how the input shaft has a polished tip with an o'ring, or the provision for one. and the electrical plug on the drivers side of the case also is another indicator.
by the looks of things, id say that the 350 was swapped in at some point in time if the truck is an 87, you even said it yourself that they quit making the th350 in 86.
 

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I owned a 1987 chevy truck with a t-350c trans.... 2 wheel drive truck.

the t-350c continued on in vehicles for export, not the USA market
 
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