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1956 Belair Sedan, Resto-Mod, Many Upgrades
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Say folk's,
Anybody out there know...

I have a 200R4 Transmission I bought from a guy, and when I pulled the pan, the valve body has a purple stripe across it. Some of my research indicated it was used in the Buick Gran National...but not sure if it was installed in Oldsmobile Cutlass's. The Transmission was VERY clean inside.

Thanks in advance...
Rods56:confused0006:
 

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Does it have the original metal tag on the outside of the case? If so what is the two or three letter code on the tag?
 

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Found This

"The most desirable TH200-4R for speed enthusiasts are the units manufactured for Buick Grand National, Olds 4-4-2 and Chevy Monte Carlo SS in 1986-'87. These units used a special valve body. They also had a larger reverse boost valve and 2nd to 3rd intermediate servo and a specially designed governor assembly. Buick units are identified by the BQ or BRF transmission codes. Monte Carlos used the CZF code. The Hurst Olds/4-4-2 units had a KZF or an OZ code. Many aftermarket suppliers offer an upgraded replacement valve body to retrofit into all TH200-4R transmissions. It duplicates the design used in these G-body transmission codes. The governor on a standard TH200-4R is designed to shift at about 3,000 rpm leading to a quick upshift through all four gears using a minimum amount of power. The specially designed governors used in the aforementioned performance transmissions are designed to shift at over 4,500 rpm making more efficient use of your engine's power band. Performance governors with this higher shift rating and the larger boost valves are available from the performance transmission parts suppliers as well."
 

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Also, check with the Buick Grand National website.....They should be able to help you ID the valve body.
 

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Many aftermarket suppliers offer an upgraded replacement valve body to retrofit into all TH200-4R transmissions.
Who are some of the "many"? Are these brand new aftermarket valve bodies? In the past, those who build these transmissions professionally always say to use the GN or SS trans; likewise those guys will pay premium $ for GN or SS cores.

Thing is, while you can modify a non-GN/SS valve body, some of the valve bores are bigger than other cores, and you can't duplicate that 100%. Plus you need the bigger valve spools.
 
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