Replacing 700R4 with TH350 questions
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Joined: Jun 2001
Posts: 920
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From: Saskatchewan
Car: 1986 Iroc
Engine: 454 Demon 850DP
Transmission: TH350, 3500 stall
Axle/Gears: 3.73
Replacing 700R4 with TH350 questions
I am getting a TH350 built up to replace my bad 700R4 in my 86 Iroc. I got the TH350 with the 9" tail shaft. Will the front yoke on my current driveshaft fit the TH350 and will I have to lenghten or shorten my driveshaft?
Joined: Mar 2000
Posts: 43,187
Likes: 46
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
The driveshaft for a 9" tailshaft TH350 will be the same length as for a TH700.
Mounting the tranny to the crossmember may be a different issue.
Mounting the tranny to the crossmember may be a different issue.
Thread Starter
Senior Member

Joined: Jun 2001
Posts: 920
Likes: 0
From: Saskatchewan
Car: 1986 Iroc
Engine: 454 Demon 850DP
Transmission: TH350, 3500 stall
Axle/Gears: 3.73
Thanks for the quick replies guys. I am glad to hear the driveshaft will fit and be the right length. I should be able to work around the crossmember mount point alright. The TH350 and 3500 stall should be ready in a week and then I will take my car to the shop for the swap. I am trying to get all my ducks in a row before the car goes in. Thanks again
Thread Starter
Senior Member

Joined: Jun 2001
Posts: 920
Likes: 0
From: Saskatchewan
Car: 1986 Iroc
Engine: 454 Demon 850DP
Transmission: TH350, 3500 stall
Axle/Gears: 3.73
I ordered the B&M TH350 swap kit. It should be here by Friday. I have read others have used this kit and it worked out alright.
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