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Old 04-04-2002, 09:11 AM   #1
dubie
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Post Swapping a 3spd to a 4 spd??

If I swap out my original 3 spd when I convert from an inline to a 350, what all has to be done? Do i need to move the cross member? do I need a different driveshaft? any clutch components needed? i'm just gathering info right now, so when i get this 350 rebuilt, i know where to go from there. Thanks again guys.

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72 C/10 LWB 2wd
250 inline 6, 3 speed column shift. Soon to have a total facelift.


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Old 04-04-2002, 10:11 AM   #2
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Well if you are talking about swapping to a SM465 (granny low) You will have to change your driveline and the hump in your cab. Everything else should be the same. WES www.ClassicHeartbeat.com

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Old 04-04-2002, 10:22 AM   #3
69 longhorn
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If you move to V8 position,I think you need to also change the crossmember under the bell.......not 100% positive,but to move the bell crossmember foward,it will also raise it up......69 longhorn.
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Old 04-04-2002, 11:27 AM   #4
okietruck
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I'm considering the same swap but with a New Process 4 speed overdrive. I have the 3.73 rear end in my '72 LWB and the overdrive would help on the highway. I've already done the I6 to V8 swap using V8 engine mounts. Would the same changes, hump & driveline, apply?
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Old 04-04-2002, 10:51 PM   #5
Fast68Chevy
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alot easier to swap to th350 from a 3 speed because of driveshaft length issues, but with the sm318(if you have that one which is what came in 67 68 250 trucks) then it wil be a yoke problem too- just like with the ch465,
no reason to move crossmember though- the bellhousing is what bolts to the x-member, no need ot move any of it unless youre replacing or moving engine,
oh and its a major pain in the ^$#%@*! to bolt the bellhousing to the crossmemeber mounts(those two bolts) when engine is bolted to the housing.
Dont be surprised if you throw some tools across garage or yard a few times in a fit, having a junk car or two and a splitting maul is a great thing toi have in those times

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Old 04-05-2002, 05:29 AM   #6
Firearmfiend
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doesn't the tranny sit farther back on an L-6? I've noticed that the shifter for a 4-speed on a V-8 comes through the hump farther forward (at the bend up toward the firewall) as opposed to the L-6 (on the flat part of the hump.

also, start looking for a bolt-in high tranny tunnel hump now... I lucked out and found one out of a V-8 2wd truck (only one hole in the hump and it's in the right place)... I even got the crome beauty ring/shifter boot ring with it and all the bolts and screws!

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'70 C-10 Short/Fleet 350 (in the family since new)
'70 C-10 Long/Fleet 307 (the Death Machine because it seems like it'll kill you to drive in it)


[This message has been edited by Firearmfiend (edited April 05, 2002).]

[This message has been edited by Firearmfiend (edited April 05, 2002).]
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