On the 200 4R vs. the 700R4 - it blows me away how much transmission misinformation is posted. What I will say is that the 200 4R is perhaps not as well understood as the 700R4. As the first mass production automatic overdrive the 200 4R suffered through all the tranny techs steep learning curve of the overdrive lock up transmissions. Few understood the throttle valve adjustment or other important aspects to the 200 4R. Not in an Avanti, I have a 200 4R in a hot rod. The trans was built about 6 years ago originally for an almost 500 hp 406 sbc. I swapped that out for a couple of different bbc's, the current 496 rang in at 681 flywheel hp. It is a serious drive anywhere pump gas 10 second street car. Same transmission - nothing changed on the trans for the last couple of engines that I blew up. There are a number of 200 4R transmissions in 9 second cars - you won't find a 700R4 at that level of speed and power. Even without using some of the race parts I have in my 200 4R do yourself a favor and spend $65 on this book http://www.ckperformance.com/resources/GM2004RTECHNICALMANUAL.html Chris tells all the secrets that the best trans builders like to keep for themselves. For lively insights on the 200 4R go to http://www.turbobuick.com/forums/transmission-talk/ or http://www.turbobuicks.com/forums/transmission-section/ Thanks to the Buick Grand National enthusiasts the best of the 200 4R is available to all. Do not let the smaller physical size of the 200 4R fool you into thinking it can't hold as much power as the 700R4 - because the opposite is true. The 200 4R has a middle bearing support like the TH400, the 700R4 does not - it is more like a TH350. The lock up on a 200 4R converter is superior becasue its natural state is locked vs. the 700R4 which uses pressure to lock up the converter. I also think the 200 4R's gear ratios are more appropriate for a V8 engine than the wide spacing on the 700R4. On a race prepped 200 4R I am not aware of any trans failures that blew the case apart - I've seen 700R4's do this. Okay, I understand that few of you race. So my advice is to go with whichever one you can get a better deal on through a quality shop with a warranty. I obviously like the 200 4R, but I will concede that you are more likely to find a tranny tech who REALLY understands the 700R4. For the guys who depend on others to do the work, that may be more important. Thomas (Cummings) +++++ Most tranny techs are boobs - seriously. Few really understand outside their generic manuals, few have really compared the guts of one trans vs. another. All that most know is how to quickly ring up the $ for common repairs. Its sad really. Most techs who heap scorn on the 200 4R are not impressed with the 700R4 either. Instead they fall back on the TH400 for which GM had invested heavily in how to build for strength. Really, GM overbuilt the TH400, so even the lowest trans tech can successfully put one behind a high performance engine. Because more education efforts followed the 700R4 more of the younger techs will be familiar with it. For those who want or need what the 200 4R can do, the links I gave are a good place to start. Funny thing (not!) is that there are many bad 700R4 trans builders out there. When their transmissions blow they will just make an excuse that is what happens with overdrive automatics. I've seen it happen that they will become silent when the 200 4R info is laid out - I've had some say that they never realized that the 200 4R and the 700R4 are opposites on how the converter clutch works. They know it, but they don't think about it. Thomas ========================== Great post Tom!!! I did much research on the 200-4R and how to make it perform. I knew about the middle bearing support and I knew the case fit the Avanti transmission tunnel in my 87 convertible where the 700R4 was 3" wider overall. I had a dozen people & shops tell me a 200-4R was crap. I knew TCI and Art Carr had refined the build to be a strong runner. I gave the TCI specs to a shop I trust and they built it for me. It cost me $1100 Cdn for the tranny & converter with no cores. Yes, I had to buy the adapter plate and I'll have to have a driveshaft fabricated, but the increase in MPG and the reduction in RPMs was what I wanted to achieve. I'll have cruise control and A/C in my R2 and I'm gonna love the ride! I'm saving your post as I believe I'll buy that publication. I still have all my research on the TCI build so the book will make a great addition to the material. Brooksie ====================== Unless you get a 200-4R from a Buick Grand National, and know that the govenor and/or valve body have not been changed you stand a HUGE risk of not knowing where your shift points will be until you actually try it. In my case, the tranny shifts at about 5,900 RPM's - about 4-600 RPM too high. I haven't blow the engine up yet, but it's scarier and hell to be pulling like a stump, then everything go flat. I've let off so many times above 5,500 RPM's because it freaks me out. I think I'm going to blow the motor. In trying to solve this issue, I've talked to many, many people. One of them - for really odd reasons - invested a lot of time to identify the over 30 different valve bodies and 18 different govenors that GM used in the 200-4R. He claims there is no chart that tells anyone what to expect when any two are put together and he claims it's almost impossible to tell what either is after they've been removed from the transmission. This guy has given me some great advice and done some other very technical things, so I have good reason to trust him. But I haven't found anyone to verify or refute what he says. In talking to TCI, I became more confused. However, I wish I had bought mine from TCI. A couple people told me they didn't trust them, but I've talked to them several times and believe they know the 200-4R about as well as anyone else. They say they've made their own valve bodies, but someone who tore one of theirs apart, says it was not more than an original GM that had been re-machined. That's okay with me, if they can predict pressures and shift points. I learned that standard GM pressure levels will not hold up to tons of torque (for very long....:-). I had my valve body reworked and got a Grand National govenor before I had pressures that were well above what GM rates. I'm hoping this works for a while. With my standard tires, I couldn't do anything below 50 MPH without either losing control or flat burning the tires away, so I bought some 17 x 8 wheels with 255-50 tires. Makes a big difference in the way the car rides and handles, plus it helps a lot to put the power down the pavement (the tire patch is 11" wide!). AND it looks awesome! Keith - I have no doubts the tranny you bought will work great for you. I'm just snake-bit. The first 200-4R I bought developed no pressure in manual 1st-2nd and in trying to solve that problem, found the center what-cha-ma-call-it was worn to the point of letting fluid by. The second tranny had that lousy valve body and mis-matched govenor. This one is working okay, so I'm not going to tempt fate again and leave well enough alone. Rich Richard Morris Renton, WA 1964 Avanti R-1 #5367 1990 Avanti 4-door #78