Want to put an automatic w/ overdrive in a ’75 Firebird? What would be the best tranny to use, the 700R4 or the 200-4R?  

The 200R4 would be easier to install as it's about the same size as the 350 but may have crossmember issues. The 700R4 would require shortening the driveshaft, getting a conversion plate from trans-dapt or another company, and would have the same issues as the 200R4 with the crossmember. I have a 200R4 i'm going to install in my '69 GTO, after upgrading some internals to the Buick GN parts. (A lot of 200R4's had the dual bellhousing pattern which allows it to bolt to either a chevy or BOP bellhousing pattern) HPP had an article on using the 200R4 in a '66 (i think) GTO or tempest about a year ago. You'll have to look into a kit for the lockup to work. Bow-tie overdrives makes some good stuff to help with the conversion. Checkout www.bowtieoverdrives.com for more info. Good luck.
Don  

Thread:   Re:automatic transmission with overdrive in a 75 firebird      <Message>:   Hello gclark, if you install a 700R4 trans behind a pontiac motor using a adapter plate , you will also have to have your torque convertor modified , when you use an adapter plate it's about 1/4" thick and that will make your convertor come out of the trans to far , and if you use washers between the convertor and flywheel it pulls the crankshaft pilot on the convertor out of the crankshaft and will cause a vibration and will eventually crack the flywheel. I've been rebuilding transmissions for 30 years , i've also got a 74 lemans sport coupe with a 700R4 trans and that what i had to do. Also you won't be able to use a dust cover around the flywheel because it puts it against the flywheel and won't bolt up without rubbing. You can make a 700R4 just a 4 speed . TRANSGO makes a valve you install in the pump and you remove the checkball out of the input shaft. The 700R4 is 3" longer than a 350 or a 2004R . You can also use this valve in the 2004R trans and eliminate the lock up. plus you have to have a convertor built without the clutch . If you need any other info on this or any other transmission question email me at tranyman1959@sbcglobal,.net , < transfriek30 >  

Tranyman,

How did you modify your torque converter?  Did you weld on 1/4" spacers?