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Discussion Starter · #1 ·
Currently I've got a 78 K20 with a fully rebuilt 454, SM465 and a 205, 3:73's and a 44front/14bolt rear. The tranny is a "manual" clutch, no hydrolics. Terribly slow shifting, and a general PITA to drive in traffic especially stuck in 2-3 hour jams in blizzard conditions on the I-70 corridor here in Colorado. I've been considering swapping to an auto. Is the Turbo 400 my only option? For those of you who have done this any advice would be appreciated. Thanks.

 

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The TH400 whould be the best choise too handle the 454. I have not done this swap but it is not that hard from what I've heard. But anyway I'll just bump this back up too the top so more people can see it/wwwthreads_images/icons/smile.gif.

/wwwthreads_images/icons/tongue.gifYodas Day Off/wwwthreads_images/icons/tongue.gif
 
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Discussion Starter · #3 ·
From what i can see you would need to get an adapater for the tranny to transfer case and either move the cross member or get another cross member. Then get either a radiator with a tranny cooler built in and a auxiliary tranny cooler or just the aux. You can buy an aftermarket floor shifter to make it easier than trying to convert the column and if you really like pushing in the clutch pedal you can leave that it there too. Anyway good luck and you shouldn't have a problem getting rid of that manual or picking up the auto....best of luck

kevin

Now I know how junkyards get started
 

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If you find a aut to drop in what would you want for the 4 speed?

IF ITS GOT WHEELS OR A SKIRT YOU CANT AFFORD IT
 
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Discussion Starter · #5 ·
Before you go and do that, consider what you have. The 465 and 205 combination are the most bulletproof that come in Chevys.....I wish I had that 205 instead of my shot 208. I know your probably not gonna swap the tcase, but the 465 will be able to handle all the torque the 454 has to offer with ease. All I am saying is that I would consider this deeply before you decide to go ahead and change an already good thing.

 
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Discussion Starter · #6 ·
The 400 is your best option but you need to get a tranny/transfer combo because your 205 can not bolt up to a turbo 400. The 205's that came behind the 400's have a different input shaft than the ones bolted to the 465's. If your truck came with a skid plate under the transfer case, you might be able to just move the cross members back some on the frame. Then modify your two driveshafts and install a tranny cooler and you'll be set. Steve

 
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Discussion Starter · #7 ·
First off, thanks for everyone's response. And, please don't get me wrong, I'm very familiar with the strength benefits of my current setup and I've been running this for the past 4 years with no probs other than the throwout bearing actually pushing through the clutch and jamming in between the pressure plates. What a mess that was and it happened about 9500ft and I had to crunch gears to get it back to denver without stopping! If I was towing with it or used it for strictly 4wheeling, I would not even be considering the swap. But now that I use the truck for more daily driving and camping/skiing excursions, the auto would be a much smoother ride. From the research I can find, a TH400 would work, but I'd much rather have the lower first gear and overdrive of the 700R4 and so people say that if built right it could handle my 500+hp big block. My only reserve is that the 465 is basically brand new, and the conversion parts to mate the 205 plus the cost of 700R4 and cooling system is adding up $$ fast.
I'm not dead set on this conversion yet hince the reason for the post, but again, I appreciate everyone's input. If anyone's running a 454/700R4/205, I would like to hear what you think of the combo, and durability. And if I decide to do the swap, I'll let you know how much I want for the sm465. Thanks again!

 

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I doubt your going to have to move your cross member. I am in the process of swapping a Th350/NP203 for a 456/205 and I don't have to move the cross member. The 456 has the 8" adapter going between it and the T-case so the length of the adapter/Trany/belhousing is equal to that of the TH350 I had in the truck before. Might be a different storry though with the TH400

Ryan

93 GMC Yukon
Chevy SuperStock 4x4 Truck Puller
Great Lakes Truck & Tractor Pulling Association
http://www.greatlakespull.com
 

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hey how much would you want for the sm465? im interested at the right price.

if you cant dodge it..it must be a tranny shop
 
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Discussion Starter · #10 ·
Not sure yet. IF I do the swap, I'll put it up for sale to recoup some cash. It's got less than 10K on it since the rebuild. Those things are everywhere though and you should be able to find one in ANY wrecking yard.

 
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