Trans/drive shaft swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cigar- · 06-22-2015, 06:59 PM

Ok....my truck was originally a six cylinder with a three speed on the column. Yup....a lighter duty truck. It now has a 350 cubic inch 300 hp V-8 motor and still the three speed though now on the floor. I hate that!!

This truck will eventually undergo a conversion to a turbo 400 transmission and will require a different drive shaft. This is where the "know-it-alls"get to chip in their $.02!!! Hopefully one or more will be those that have done the same exact swap so they know what I need to do!!

I have been given all kinds of information about this. Go to a one piece shaft....stay with a two piece shaft....the support bearing is weak on the light duty trucks, get rid of it.....if the support bearing is weak, why not upgrade to a 3.4 ton bearing? There are simply so many variable.

This truck might pull an occasional load of heavy stuff once in a while. It may even one day tow a small travel trailer....who knows. Mainly its a beater to drive around a throw crap in the back and drop it off somewhere else. I ain't going drag racing with it.....Farm Boy (or whatever his name is) won't ever see the tail lights on this truck.

I just need some good HONEST credible advice about finding the right drive shaft for the truck. And yes....it's a 1971 with trailing arm rear suspension.

Thank you in advance for all of the advice. The last guy to help me out got a $25.00 gift card.

brad_man_72 · 06-22-2015, 09:17 PM

Have one made that fits your custom truck.

hamjet · 06-22-2015, 10:37 PM

First, was the 8 cyl moved up to the 8 cyl. position or is it in the 6 cyl position still. the 3 speed manual is 27 3/4 long, the 400 comes in 3 lengths. 28 3/8, 33 3/4, and 37 7/8... It looks like it will have to be cut down in any case. No reason you can't stay with the 2 piece, (just my opinion) and just get the front piece cut, welded and rebalanced. the 400 is 32 spline whereas the 3 manual is 27..

hamjet · 06-23-2015, 07:02 AM

"IF" you didn't get the 400 yet then go with the 200-4r, trannys are the same length, complete bolt in, same driveshaft as the 3 speed manual, plus you now have overdrive. thats what I just did, couldn't be happier. just a thought...

cigar- · 06-23-2015, 03:45 PM

Now this is some great information !! I had no idea about the position of the 6 cylinder versus the 8 cylinder motor. Since I didn't do the initial swap, I can only assume (yeah, I know what that does !!) that the 6 cylinder mounting position was used. I have no idea how long ago the swap was done so I have no help there. Without knowing more about dimensions from the factory, I'm unable to comment further on that.

I will look into the 220r trans as an option. Really what I was after was just a an easy swap into an automatic transmission but this project appears to be more involved than what I expected. Nonetheless I will proceed slowly to completion.

Above all, I thank any and all that contribute to helping me solve my problem.

06-22-2015, 06:59 PM	#1
cigar- Registered User Join Date: Aug 2013 Location: Smith, NV Posts: 110	Trans/drive shaft swap Ok....my truck was originally a six cylinder with a three speed on the column. Yup....a lighter duty truck. It now has a 350 cubic inch 300 hp V-8 motor and still the three speed though now on the floor. I hate that!! This truck will eventually undergo a conversion to a turbo 400 transmission and will require a different drive shaft. This is where the "know-it-alls"get to chip in their $.02!!! Hopefully one or more will be those that have done the same exact swap so they know what I need to do!! I have been given all kinds of information about this. Go to a one piece shaft....stay with a two piece shaft....the support bearing is weak on the light duty trucks, get rid of it.....if the support bearing is weak, why not upgrade to a 3.4 ton bearing? There are simply so many variable. This truck might pull an occasional load of heavy stuff once in a while. It may even one day tow a small travel trailer....who knows. Mainly its a beater to drive around a throw crap in the back and drop it off somewhere else. I ain't going drag racing with it.....Farm Boy (or whatever his name is) won't ever see the tail lights on this truck. I just need some good HONEST credible advice about finding the right drive shaft for the truck. And yes....it's a 1971 with trailing arm rear suspension. Thank you in advance for all of the advice. The last guy to help me out got a $25.00 gift card.

06-22-2015, 09:17 PM	#2
brad_man_72 the boat guy Join Date: Jul 2007 Location: springfield mo Posts: 2,339	Re: Trans/drive shaft swap Have one made that fits your custom truck. __________________ 67, swb, fleet, tach, throttle, 5.3, 4l60e, 3.73's, fuel cell, 5 lug, p.d.b., 4-6 drop. great little truck 66, stevens drag/ski 18' silouette, 350, 2.02 doublehump heads. comp extreme marine 278 cam, vette 7 fin valve covers, old polished edelbrock intake, velvetdrive, casale v-drive, adj cavitation plate. 28, model a rpu project,

06-22-2015, 10:37 PM	#3
hamjet Registered User Join Date: Apr 2013 Location: South Westerlo, New York Posts: 1,325	Re: Trans/drive shaft swap First, was the 8 cyl moved up to the 8 cyl. position or is it in the 6 cyl position still. the 3 speed manual is 27 3/4 long, the 400 comes in 3 lengths. 28 3/8, 33 3/4, and 37 7/8... It looks like it will have to be cut down in any case. No reason you can't stay with the 2 piece, (just my opinion) and just get the front piece cut, welded and rebalanced. the 400 is 32 spline whereas the 3 manual is 27.. __________________ Thanks, Joe.. 1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB.

06-23-2015, 07:02 AM	#4
hamjet Registered User Join Date: Apr 2013 Location: South Westerlo, New York Posts: 1,325	Re: Trans/drive shaft swap "IF" you didn't get the 400 yet then go with the 200-4r, trannys are the same length, complete bolt in, same driveshaft as the 3 speed manual, plus you now have overdrive. thats what I just did, couldn't be happier. just a thought... __________________ Thanks, Joe.. 1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB.

06-23-2015, 03:45 PM	#5
cigar- Registered User Join Date: Aug 2013 Location: Smith, NV Posts: 110	Re: Trans/drive shaft swap Now this is some great information !! I had no idea about the position of the 6 cylinder versus the 8 cylinder motor. Since I didn't do the initial swap, I can only assume (yeah, I know what that does !!) that the 6 cylinder mounting position was used. I have no idea how long ago the swap was done so I have no help there. Without knowing more about dimensions from the factory, I'm unable to comment further on that. I will look into the 220r trans as an option. Really what I was after was just a an easy swap into an automatic transmission but this project appears to be more involved than what I expected. Nonetheless I will proceed slowly to completion. Above all, I thank any and all that contribute to helping me solve my problem.



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