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Discussion Starter #1
I swapped out the 307 Olds for a 350 Chevy and now I'm taking out the 200R4 and replacing it with a rebuilt TH350. My question is what drive shaft and transmission mount changes I need to make? Any insight and responses are welcome and greatly appreciated, Thanks Brian
 

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Ratty yet Fancy
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the swap

As long as you have a TH350 with the right bell housing bolt pattern for your engine it is a very simple swap. If you have a chevrolet 350 you need a trans with the chevrolet bell housing. If you have a pontiac/buick/olds 350 you need the pontiac/buick/olds bellhousing.

The easy way to tell is the top of the bell housing, the chev one comes to a peak at the top and the other one has a much lower top to clear some of the distributor mounts of the pontiac/buick/olds engines.

I bet you've already figured that out, but just in case there it is haha.

The torque converters from a TH350 will bolt up to your stock flex plate that is used for your stock 200r4. I am currently running a converter from a 1974 corvette because of the stronger vanes in it and a 1800 rpm stall rather than a 1600 rpm stall you get from the camaro/firebird torque converter. The choice is really up to you as to what you want to run.

Other than that your biggest problem is the cross member for the transmission mount. The stock 200r4 mount is at least 6 inches further towards the rear axle the one on the TH350. The good news is the output shaft is the same between your two transmissions, so the original drive shaft should work without any issues. I am running the original drive shaft in my car without any problems.

There are a few things you can do about the cross member, I lacked the time to fabricate my own modified setup to make it work properly. luckily these cars originally ran TH350's in older caprice's at one point so there is another set of mounting holes in the frame further up the driver side of the frame towards the engine. You can actually use the stock 200r4 cross member using the other further forward two holes on the driver side with the original mounting holes on the passenger side. The only iffy part is you can only use bolts through two of the four holes, and it sits on an angle between the frame rails. For my stock 307 it can take it, but don't put too much power to it or any solid transmission mounts or it will come apart.

To do it right, you should either find an older th350 B-body cross member and bolt it in, or fabricate a proper cross member that will hold up to the stress of a strong 350 and a built transmission (in your case). But the crooked mounting set up to get it going, but it's definitely not a long term solution.
 

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Discussion Starter #3
Thanks for the info, but from the info I gathered the 200R4 and TH350 transmisions have different lengths. We can fabricate the the trans mount if necessary, I really hope my drive shaft will work... and by the way cool Safari Wagon I like it! :^)
 

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Ratty yet Fancy
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If they are different lengths from bellhousing to output shafts between the 200r4 and the TH350 the difference is very little. I currently have about 15000 km's on the setup with no issues whatsoever.
 

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why give up overdrive and lockup?
 

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It's because it is the second 200R4 I've had in my wagon that has gone bad, and the guy that rebuilts our transmissions says they're junk and a rebuilt TH350 would be better in the long run. As far as gas milelage I'm not concerned considering I paid $1200 for my wagon 12 years ago. And most of the driving I do is in town and I drive like a Grandpa anyway, Haha.
 

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Art carr performance played with the 2004r for the gbody Grand National to make them holdup well behind the boosted motor, so there are some parts out there for them. Biggest killer especially for overdive transmissions is heat so aftermarket external cooler is a must in my book.
 

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LOTS of companies make the 200R4 last in the Grand Nationals and other cars. If someone with a mild car has problems with that tranny the BUILDER is just incompetent. REALLY REALLY common for "professional" tranny builders to be incompetent.
 

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LOTS of companies make the 200R4 last in the Grand Nationals and other cars. If someone with a mild car has problems with that tranny the BUILDER is just incompetent. REALLY REALLY common for "professional" tranny builders to be incompetent.
I wouldn't be so quick as to blame the rebuilder right away. The 2004R in stock form has more weaknesses than say a 700r4. The pump on mine grenaded, I know those are common, it's all over the internets. Put the right parts in a 200r4 and it's bound to run fine in a boosted car such as the GNs. My tired old 307 managed to kill a factory 200r4 so to say the rebuilders are the issue is almost irrelevant. A stock 200r4's weaknesses are more so the issue at hand here.
 

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I wouldn't be so quick as to blame the rebuilder right away. The 2004R in stock form has more weaknesses than say a 700r4. The pump on mine grenaded, I know those are common, it's all over the internets. Put the right parts in a 200r4 and it's bound to run fine in a boosted car such as the GNs. My tired old 307 managed to kill a factory 200r4 so to say the rebuilders are the issue is almost irrelevant. A stock 200r4's weaknesses are more so the issue at hand here.
I agree with you on these transmissions being weak. I always heard the sun gear shell was very soft in the 2004r.

From past experience, having an AOD rebuilt for my Mercury Cougar, the rebuilder is usually open to suggestions of upgrades you may want done to the transmission to make it more durable. I researched common problems and solutions that are known to cure the weak spots in the transmission I was wanting rebuilt. For instance, I opted for a wider overdrive band that Ford start placing in later model overdrive transmissions (AODE/4RW70), stronger clutch materials, bigger servos and a wider shift ratio. I then sat down with the owner of the shop and we discussed what I wanted and he showed me the prices to upgrade and what was already included as upgrades to the 1988 AOD for my car, then ordered everything he did not have on hand.

Usually a good reputable transmission shop will have bulletins of some updates that have been recommended for the particular transmission they are rebuilding. Some may just flush the converter and rebuild it with a general rebuild kit for that transmission, fill it back up and call it rebuilt but others usually want the component to last at least the life of their warranty (if they issue one) and will make sure the TV cable is mounted properly and pressure is set before it leaves the shop. Mine even had me come back after 100 miles to make sure everything was breaking in properly and checked fluid.

Like I stated before and I am sure others will agree with me, HEAT is the #1 offender to any transmission, especially ones that sucked out of the gate to begin with! Throw a good aftermarket cooler inline with your radiator cooler, make sure to use the recommended transmission fluid, never flush a higher mileage or older transmission at one of those oil change lube shops instead drop the pan, change the filter and fluid every 30k miles or so and make sure the tv cable pressure is correct periodically to make it last.
 
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