Visit this site:
http://members.aol.com/powerrslid/thm2004r.html
It lists IDs for 200-4Rs. ID tags are found on the passenger side of the output shaft housing. Any of the IDs that are in bold print on this page are the desirable ones. These 200-4Rs were basically built in two configurations. The non-bold applications shifted at 3500 rpms...wide open throttle! They also had weak line pressures and soft shifts making them a little less reliable. The bold applications were behind H.O. or turbo applications and were alot better. They shift at more like 5000-5500 rpms at WOT, and are firmer and more reliable. If they could reliably push a GNX to stock 12-second times, they'll handle alot.
The differences are pretty fundamental, meaning its not easy to modify a non-bold application to perform like a bold one. They had different governors, valve bodies, the works.
The "weak" 200-4R is mostly responsible for two stereotypes: 1) that the 200-4R is a weak tranny, and 2) that the Olds 307 is a bad motor. Nothing is worse than a weak 200-4R behind an 87 307. (this is the exact combo that I have) The weak tranny couldn't even hold the 140 hp from the 307, and the 307 couldn't perform below 3500 rpms. They needed a little more port volume and they needed to be free to rev to 4200.
Don't fret about finding one. Of the two 'yards I've visited recently, they both had a couple examples of an H.O. 200-4R.
Most of the 200-4R trannys I've seen are truly universal, having both GM bolt patterns. This was due to gas crunches in the 80s. The 200 family is much smaller and lighter compared to the 350/700 family. For a while, Chevy only had the 700 to use for O/D and the BOPs only had the 200 family. By making the 200-4R universal, they could use the lighter, more fuel efficient 200 family in all GMs.
Don't confuse the sometimes decent 200-4R with the always pathetic 200 three speed. Oh, BTW... when modifying a lock-up OD 200-4R for a non-computer application, its necessary to make a very easy modification to get the TC to lock up. Any competent tranny shop can install a pressure switch that will lock up the TC whenever the 4th gear circuit is pressurized. Its simple, fool proof, and I'm thinking of doing it to mine even though I still have the computer for simplicity's sake.
A quote from a performance 200-4R site: "Though the 200 gained a reputation as an undependable transmission early on in its life, most of this attributable to the early lock-up torque converter designs, the 200-4R is being used by and adapted to cars that demand a reliable overdrive, rear wheel drive transmission for high performance use. This transmission has surprised many transmission technicians that were used to seeing the many failing 200s. Many vehicles that are pumping out in excess of 700 horsepower are still using the 200-4R. The next step up being the mainstay THM 400."
Another quote from a different site: "If you note, the engine torque rating for the TH-200-4R and the TH-700-R4 is very close in stock form. Considering the weight advantage, the gear ratio preference, deeper overdrive, and the fact that the TH-700-R4 only comes in Chevy bolt pattern, the TH-200-4R is preferable for most BOPC street applications when built properly."
Here are a few more performance links for this tranny:
http://www.gnttype.org/techarea/transmission/200rebld.html
http://my.inil.com/~dlbrown/oft200.htm
http://www.drwtransmission.com/thm_200-4r.htm
http://my.en.com/~thall/olds/oftrn.htm
http://www.transmissioncenter.net/200-4R.htm
Good luck
Curtis Mittong
