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200-4R Installation

Time to overdrive your T/A

I have just purchased a 200-R4 to install in my T/A and will be outlining my install here.

Important facts.

Flywheel holes for will need to be enlarged for the new metric bolts. NOT! My flywheel did not need this.

Trans mount bolt hole spacing is different. Most replacement mounts are slotted to fit both.

Output shaft is 27 spline just like the Turbo 350.

Turbo 400 uses 32 spline.

The transmission is the same length as the turbo 350, but the trans mount is on the very 

end of the transmission so the cross member will need to be moved back about 5".

Trans cooler line fittings are the same thread, but will need to be relocated.

A bracket will need to be fabricated for the TV cable.

You will need an overdrive shifter I have found two choices the Shifterworks kit and the B&M Megashifter.

The  Shifterworks kit is a very nice kit that includes everything you need to update your shifter

and the linkages you need for the shifter to transmission mounting. 

Here is the B&M Megashifter console version that will work with a 200-R4.

  A B C D E  
Trans  Length Length Length Spacing Width Spline
Type Overall Bell/H to Tail/H Bell/H to Mount Mount Bolts At Bell/H Count
ST-300 27 11/16" 20 7/16" 20 1/8" 3 3/4" 19 1/8" 27
TH400 28 1/2" 24 5/16" 26 13/16" 4 1/4" 19 3/8" 32*
TH200-4R 27 3/4" integral T/S 26 13/16" 3 3/4" 19 3/8" 27
TH700-R4 30 13/16"** 23 7/16" 22 5/16" 3 3/4" 19 5/16" 27
* Some 27            
** Vette 29 3/4            

Check out  High Performance Pontiac April '98 for the start of a six part series on how to install an overdrive.


GM Automatic Transmission Overhaul.

Links for Trans parts etc.

Shifterworks kit

Precision Industries


Art Carr


Gear Ratios and how to rebuild your 200 R-4


GN T-Type web site. Info on the 200R-4

Transmission gear ratios

A good article on putting a 200 R-4 in a GS.


Feel free to drop me a note. * I am looking for some good articles for the third and fourth gen birds. If you have any that you would like to see on this site send them to me and I will post them on my site.     

  • The information in here is just an outline.
  • The author claims no responsibility for the info contained in these pages. 
  • If unsure of any tip or modification seek a professional for the job.
  • In some states this may violate pollution laws
  • Check with your state on the laws.
  • Not affiliated with Pontiac or General Motors