# Can I use a Cadillac 200-4R trans?



## Reb (Aug 5, 2013)

HELP!!!! My husband has convinced me to swap out my car's 2-speed automatic for a more-modern 200-4R AOD. So, today we went to his favorite salvage yard in search of a suitable transmission. 

Well, we searched and searched and searched, but no luck except for one, which is still in the car - a Cadillac. I forget the exact year, but it was within the years indicated in the Hemmings article GM TH-200-4R Transmissions | Hemmings Motor News, and so should have the BOP bellhousing, too. Plus, per the salvage yard's data, it had the correct, 16-bolt pan, and no bolt-on tailshaft. 

The only thing which stopped my husband from buying it on the spot was the presence of an *electrical plug on the lower left front of the transmission's body *(we had hoisted the car up in the air for a look-see).

So, the question is - what does that plug do? Does it mean the Caddy used an electrical torque converter lockup process? If so, will the aftermarket lockup adapters replace this electrical setup, if that's what the plug on the Caddy does?

HELP!


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## jmt455 (Mar 26, 2012)

Yes, that connector is for a lock-up torque converter.

Any of the aftermarket lock-up kits should work fine with that transmission; just get one that is designed to work with the 200-4R transmission.

You'll also need to investigate cross-member and transmission mount differences, as well as driveshaft length and yoke/spline differences. You will also need to install a TV (throttle valve) cable, with the proper geometry at the carb throttle linkage. The TV cable must be set up and installed correctly; improper alignment or miss-adjustment will lead to premature transmission failure.

This site is helpful with all of those items: High Performance Automatic Transmissions & Parts - TCI® Auto

I would also caution you that the 200-4R is not known for its durability in high-torque applications, so you might want to rebuild the used transmission with high performance parts OR use an adapter plate and go with a 700-R4 transmission.


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## kilkm68 (May 5, 2011)

I have a 200 4R in my 68 GTO behind a 500+ hp Pontiac 474. In stock form the 200 won't last with a high torque/ho motor but can be built to handle 1000 hp. They also have a better gear set than the 700 R4 and mine uses a single wire to the plug to lock up the torque converter. Proper TV cable adjustment and geometery are critical with these transmissions, you can smoke them in short order if its wrong. Check out Extreme Automatics Where winning is easy for much info on there excellent products and tech info.


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## Reb (Aug 5, 2013)

68 & 455 - Thank you both SO much. This enables us to move forward on a pre-determined timetable. We're headed to Summit today (Tallmadge store is about an hour from us) to purchase the Lock-Up Kit and TV Cable Kit. 

Have already spoken with transmission shop which is going to rebuild 200-4R to handle my car's approximate 300 hp. They also know all about installation and adjustment of the mate-up components, plus relocating trans mount and driveshaft/yoke mods. 

Your information is invaluable. I really, really appreciate it. 

BTW - both your cars are GORGEOUS. We were at TP Tools yesterday, and checked out their collection, which includes an immaculate '67 GTO. Really got me anxious to get mine completed. Shopping colors, too. More soon!


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## Rukee (Feb 8, 2007)

Be sure to post up your results of the trans swap.


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