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Old 02-06-2019, 11:17 PM   #1
67ranchhand
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4x4 sm420 to sm465 208 case

Hello everyone, I have a 67 k10 with the sm420 and Rockwell case. I am going to drive this truck as much as I can. Maybe a daily driver. For reliability purposes and since the parts are hard to find for this trans and case, I was thinking about swapping it out with a 265/208 case. I have this trans in a square body with a cracked head 6.2 diesel. I would rather have the 205 but this is what I have. Has anyone done this swap? Is this a bolt in or are there modifications that need made? Driveshaft length? Mounting? Thanks guys!
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Old 02-06-2019, 11:31 PM   #2
sweetk30
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Re: 4x4 sm420 to sm465 208 case

shafts more than likely yes need lengths changed .

floor shifter is different as the 208 unit bolts to the floor pan over the older rockwell/203/205 stuff just passing threw .

otherwise i dont know the rest as i am a auto trans guy .
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Old 02-07-2019, 02:25 AM   #3
kwmech
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Re: 4x4 sm420 to sm465 208 case

Grab all the parts from the square body from the bellhousing back. Modify the floor for the shifters and have the driveshafts rebuilt to length. Actually not bad of a swap since you already have all the parts available. The only thing that you may have to keep would be the clutch fork from the 67 into the aluminum bellhousing
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Old 02-09-2019, 08:23 PM   #4
Mike C
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Re: 4x4 sm420 to sm465 208 case

You will need the bellhousing form the square body as well. The SM420 has the smaller size bearing retainer. Same size as 3 speed and car 4 speeds while the SM465 is larger and needs bigger pilot hole.
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Old 02-11-2019, 08:29 PM   #5
67ranchhand
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Re: 4x4 sm420 to sm465 208 case

Thanks for all the reply's guys. When the weather breaks I will have to drag the old square out and do some investigating. Thanks again!
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Old 02-11-2019, 10:43 PM   #6
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Re: 4x4 sm420 to sm465 208 case

Should be pretty straight forward with all the parts you have. Would suggest converting the 208 to fixed yoke if needed as most Chevy 208's are slip yoke style.
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Old 02-12-2019, 06:59 PM   #7
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Re: 4x4 sm420 to sm465 208 case

Quote:
Originally Posted by Richard View Post
Should be pretty straight forward with all the parts you have. Would suggest converting the 208 to fixed yoke if needed as most Chevy 208's are slip yoke style.
no kits for this . its a half dodge and gm case to do it with some work involved .
if its a np241 then there is kits for that case .
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Old 02-12-2019, 10:38 PM   #8
67ranchhand
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Re: 4x4 sm420 to sm465 208 case

Thanks guys for the tip. Iím pretty sure itís a 208 but wonít know for sure until I drag it out from its 6 year resting place! What is the advantage of the fixed yoke? To have a carrier bearing? Thanks again.

Brett
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