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OleBlue79 · 08-10-2010, 11:41 AM

I was fooling with the idea of installing a 700R4 in my 79 C-20. I went to a local driveshaft shop and he said he could shorten and balance a drive shaft for 100 bucks. Not too bad. It would be easier and cheaper to shorten one than to try to lenghten one. You may still have 150K on it since the odometers did not have the 6th digit. When they got 99,999.9 they just rolled over and started at 00,000.0. Mine was showing 5000 miles on it when I got it. God only knows how many times its zeroed itself. Good luck with your project.
A little more advice. I would reuse the same fluid in the trans. Alot of times, if they haven't been serviced regularly and there are a lot of miles on them, they will burn up with new fluid. I do not know why. I just know they will.
If you want to improve your shifts with the TH-400 or a TH-350 without spending any money, you can screw in on the little screw inside the vacum modulator valve. Don't go over 4 rounds. I went in on mine 3 rounds and it shifts a lot better. Takes a little more RPM to get it to shift.

08-10-2010, 11:41 AM	#8
OleBlue79 Registered User Join Date: Jan 2010 Location: Louisiana Posts: 127	Re: Need some help / 400 VS 350 Transmission I was fooling with the idea of installing a 700R4 in my 79 C-20. I went to a local driveshaft shop and he said he could shorten and balance a drive shaft for 100 bucks. Not too bad. It would be easier and cheaper to shorten one than to try to lenghten one. You may still have 150K on it since the odometers did not have the 6th digit. When they got 99,999.9 they just rolled over and started at 00,000.0. Mine was showing 5000 miles on it when I got it. God only knows how many times its zeroed itself. Good luck with your project. A little more advice. I would reuse the same fluid in the trans. Alot of times, if they haven't been serviced regularly and there are a lot of miles on them, they will burn up with new fluid. I do not know why. I just know they will. If you want to improve your shifts with the TH-400 or a TH-350 without spending any money, you can screw in on the little screw inside the vacum modulator valve. Don't go over 4 rounds. I went in on mine 3 rounds and it shifts a lot better. Takes a little more RPM to get it to shift.