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Old 10-23-2017, 06:01 PM   #1
35boulder
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Change over From 3OT to Automatic

Hello all. I'm looking at changing my '69 SWB from 3OT to automatic. Reason being that I'm needing a throw out bearing which could mean clutch work and flywheel. I have seen some great threads where someone has listed the steps needed to do certain swaps. So rather throw a bunch of cash into fixing this problem I am considering this swap. Was wondering if anyone could help me thru this.
Thanks for the help.
Dave
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Old 10-23-2017, 06:49 PM   #2
randy500
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Re: Change over From 3OT to Automatic

Short shaft th350should use the same driveshaft and yoke.
You will need
1. 4piece shift linkage
2. Transmission crossmember, remove your bellhousing crossmember, it’s riveted in, 8 rivets I think, slice a “x”in each rivet with a cut off blade on a 4.5”grinder then cut rivet head off with cold chisel or air chisel(preferred)
3. Automatic steering column.
4. Transmiission lines and vac modulator line. Vac modulator fitting for intake manifold.
5.Check your radiator to see if it has trans cooler fittings, otherwise use Aux. cooler in front of radiator.
6. Transmission detent cable bracket which mounts to intake manifold bolts. Detent cable stud for carb.
7. Transmission complete with detent cable.
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Old 10-24-2017, 09:01 AM   #3
35boulder
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Re: Change over From 3OT to Automatic

Thanks for the list.
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Old 10-24-2017, 10:39 AM   #4
MARKDTN
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Re: Change over From 3OT to Automatic

I would use a radiator that has a cooler in it with an extra external one, especially if towing. The internal coolers are much more effective at cooling trans fluid than just an external.
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Old 10-24-2017, 10:53 AM   #5
Coley
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Smile Re: Change over From 3OT to Automatic

Definitely with all of the above including finding a radiator that is set up for the trans cooling lines.
One thing i would do those is move from a TH350 to a 700R to get the advantage of the 4 speed automatic, which is what a lot of guys with the automatic trucks are doing lately....a very popular upgrade.
You'll have it apart anyways so you will have an easy choice for either.

All good
Coley
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Old 10-27-2017, 03:00 PM   #6
bigmac73
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Re: Change over From 3OT to Automatic

I did this once about 20 years ago, my concern here is your gear ratio in the rear end. you might want to check this out when I did the swap for some reason the thing was a dog of the line ( could have been the 307) but once I swapped in a 300hp 350 crate motor and added a 2200 stall converter, the off the line really pepped up a bit.

some thing to think about and for discussion on the forum.

now on the other hand the current 72 I have now came with 3.08 gears and a 350/th350 but it had way more off the line pep then my old one, but since then I have changed out them gears out with a eaton unit and 3.73 set of gears
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Old 10-27-2017, 03:31 PM   #7
35boulder
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Re: Change over From 3OT to Automatic

Thanks for the replies. It all helps.
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