Replacing my 4sp with a different 4sp need help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

harrdawg54 · 07-01-2007, 12:20 AM

I have a 1969 C20 custom camper and the transmission needs to be rebuilt. I found a 4sp that I can get dirt cheap and install until I get the other one rebuilt. So, here is my question. I have a 350 and the tranny is coming out of a 68 SWB with an inline 6. I have no idea what make the tranny is so..... I need to know if there is going to be a problem putting it in my truck, and what extra things might be involved besides changing over the bellhousing. Any help would be great.

Thanks

JimKshortstep4x4 · 07-02-2007, 04:54 AM

Welcome to the board from West Michigan!

Do you have a 350 engine or do you mean a TH 350 transmission?

Jim

Gray Ghost · 07-02-2007, 07:23 AM

First thing to do is ID the new tranny, then you will know what is needed. If it's a Muncie or Saginaw, it should bolt right up. If you already had a 4 speed, the install will be a breeze....if not you need a host of parts to make the swap work.

harrdawg54 · 07-03-2007, 12:09 AM

Thanks for the welcome. I have a small block 350 and a 4 speed manual transmission. My truck is a 4x4 and I think the truck that I would be getting the new tranny from is only 2 wheel drive. I will be taking a look at it tomorrow. My existing tranny is very bad. All the seals are bad, it seems that the previous owner didn't want to go under the truck to fill the gear oil and filled it through the shifter, and put a little ( and by a little I mean A LOT) too much in. When I shift into neutral when I am coming to a stop you can hear the gears chatter. When I drive you can hear the gears whining. Thanks for all the help.

P.S.> This is a great site, I have already done the headlight mod and converted my alt.

1969k10stepside · 07-03-2007, 12:14 AM

Both should be SM465 trannys.Putting a 2wd tranny in a 4wd truck...that would require a divorced t-case or you could just put in the 2wd tranny and rear driveshaft and not have 4wd until the other is rebuilt.If they are both 4wd then its a simple swap.No swapping driveshafts for shorter ones,moving crossmembers,etc

68C15 · 07-03-2007, 06:40 AM

this may be of some help
http://go.mrgasket.com/pdf/trans_id.pdf

harrdawg54 · 07-09-2007, 09:45 PM

Thanks for all the help. I guess I will just keep looking for a different 4 speed.

07-01-2007, 12:20 AM	#1
harrdawg54 Registered User Join Date: Apr 2007 Location: Sandpoint, Idaho Posts: 178	Replacing my 4sp with a different 4sp need help I have a 1969 C20 custom camper and the transmission needs to be rebuilt. I found a 4sp that I can get dirt cheap and install until I get the other one rebuilt. So, here is my question. I have a 350 and the tranny is coming out of a 68 SWB with an inline 6. I have no idea what make the tranny is so..... I need to know if there is going to be a problem putting it in my truck, and what extra things might be involved besides changing over the bellhousing. Any help would be great. Thanks

07-02-2007, 04:54 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Replacing my 4sp with a different 4sp need help Welcome to the board from West Michigan! Do you have a 350 engine or do you mean a TH 350 transmission? Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

07-02-2007, 07:23 AM	#3
Gray Ghost Senior Member Join Date: Sep 2004 Location: Terrell, TX Posts: 1,967	Re: Replacing my 4sp with a different 4sp need help First thing to do is ID the new tranny, then you will know what is needed. If it's a Muncie or Saginaw, it should bolt right up. If you already had a 4 speed, the install will be a breeze....if not you need a host of parts to make the swap work. __________________ Kelly '05 GMC Sierra SLE Z71 Bone stock except for new bed rail caps.

07-03-2007, 12:09 AM	#4
harrdawg54 Registered User Join Date: Apr 2007 Location: Sandpoint, Idaho Posts: 178	Re: Replacing my 4sp with a different 4sp need help Thanks for the welcome. I have a small block 350 and a 4 speed manual transmission. My truck is a 4x4 and I think the truck that I would be getting the new tranny from is only 2 wheel drive. I will be taking a look at it tomorrow. My existing tranny is very bad. All the seals are bad, it seems that the previous owner didn't want to go under the truck to fill the gear oil and filled it through the shifter, and put a little ( and by a little I mean A LOT) too much in. When I shift into neutral when I am coming to a stop you can hear the gears chatter. When I drive you can hear the gears whining. Thanks for all the help. P.S.> This is a great site, I have already done the headlight mod and converted my alt.

07-03-2007, 12:14 AM	#5
1969k10stepside Registered User Join Date: Mar 2006 Location: USA Posts: 21,019	Re: Replacing my 4sp with a different 4sp need help Both should be SM465 trannys.Putting a 2wd tranny in a 4wd truck...that would require a divorced t-case or you could just put in the 2wd tranny and rear driveshaft and not have 4wd until the other is rebuilt.If they are both 4wd then its a simple swap.No swapping driveshafts for shorter ones,moving crossmembers,etc Last edited by 1969k10stepside; 07-03-2007 at 12:15 AM.

07-03-2007, 06:40 AM	#6
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	Re: Replacing my 4sp with a different 4sp need help this may be of some help http://go.mrgasket.com/pdf/trans_id.pdf

07-09-2007, 09:45 PM	#7
harrdawg54 Registered User Join Date: Apr 2007 Location: Sandpoint, Idaho Posts: 178	Re: Replacing my 4sp with a different 4sp need help Thanks for all the help. I guess I will just keep looking for a different 4 speed.

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