1972 Blazer transmission swap? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TX72K5 · 01-20-2006, 01:15 AM

I am wanting to change (swap) out a 4 speed manual transmission with a automatic 350 turbo trans. Will the transfer case from the manual trans mate to the 350 turbo trans and vice versa? Also are the transmission braces the same on an auto and standard? Mike

BobbyK · 01-20-2006, 01:41 AM

No problems with the transfer case,it's the adapter that goes in between the trans and T/C that's different.
the th350 adaptor is on the left,the sm465 adaptor is on the right.

here is an article on swapping a manual (SM465) to automatic (TH350) conversion.
http://www.geocities.com/spencerhut/...trans_swap.htm

TX72K5 · 01-20-2006, 02:34 AM

Thank you for the info. Mike

Gyva · 01-20-2006, 04:09 AM

so if you change out a manual on an old 65 2 wheel drive with an auto TH350 will you be forced to get a new driveline because of the different lengths trannys?

something I was wanting to do eventualy.

Mike...

Blazer1970 · 01-20-2006, 07:40 AM

The transfer case that was attached to the SM465 has a 10 spline input, you will need to find a case with a 27 spline input to use behind the TH350 or change the input in the t-case you have.

orange72blazer · 01-20-2006, 08:22 PM

Quote:

Originally Posted by TexasWreck

I am wanting to change (swap) out a 4 speed manual transmission with a automatic 350 turbo trans. Will the transfer case from the manual trans mate to the 350 turbo trans and vice versa? Also are the transmission braces the same on an auto and standard? Mike

I did this swap in my Blazer a couple of years ago. You will need the TH 350 adapter, sleeve, and 27 spline input shaft for the transfercase. You will have to take the 10 spline input shaft out of your t-case and replace it with the 27 spline shaft, or get a t-case that is already set up for an TH350, I just swapped the input shaft an mine it was a lot cheaper than a different t-case and a fairly simple thing to do. The crossmember mounts in the same location. You will also need a new starter, I used a stock one from a 1999 Chevy truck, it is a lot smaller and has more torque, and is only $100 brand new. The manual to auto swap took a while but was a lot eaiser than I thought it would be.

**special-K** · 01-21-2006, 12:24 PM

Try to find a complete unit:TH350/adaptor/205.It`ll bolt right in and you can sell your complete 4spd unit for a trail-rig.

ajbirken · 01-21-2006, 06:34 PM

It's pretty funny.

I have a TH350 in mine and would love an sm465.

TX72K5 · 01-22-2006, 12:27 PM

Quote:

Originally Posted by ajbirken

It's pretty funny.

I have a TH350 in mine and would love an sm465.

Where you at? If you are close to Fort Worth, Texas I would trade. Mike

ajbirken · 01-22-2006, 08:50 PM

Quote:

Originally Posted by TexasWreck

Where you at? If you are close to Fort Worth, Texas I would trade. Mike

I am in Raleigh NC. A bit far. Shipping would probably kill any "deal".

**special-K** · 01-22-2006, 08:44 PM

That`s what I was wonderin`.PM that guy to make sure he knows your interest.

crispy · 01-23-2006, 01:59 PM

i just did the opposite swap... interesting side note, i didn't have to have my drivelines altered at all... i thought for sure that i would have had to

Scrubby · 01-25-2006, 07:35 PM

Quote:

Originally Posted by crispy

i just did the opposite swap... interesting side note, i didn't have to have my drivelines altered at all... i thought for sure that i would have had to

The sm465/np205 is the same length as the TH350/np205, so the drivelines don't have to change.

TX72K5 · 01-25-2006, 09:48 AM

Will a 700R4 bolt up to the 1972 transfer case?

BobbyK · 01-25-2006, 11:05 AM

With a output shaft modification,yes.

01-20-2006, 01:15 AM	#1
TX72K5 Junior Member Join Date: Jan 2006 Location: Fort Worth, Texas Posts: 57	1972 Blazer transmission swap? I am wanting to change (swap) out a 4 speed manual transmission with a automatic 350 turbo trans. Will the transfer case from the manual trans mate to the 350 turbo trans and vice versa? Also are the transmission braces the same on an auto and standard? Mike

01-20-2006, 01:41 AM	#2
BobbyK Registered User Join Date: May 2000 Location: Petrolia,Ontario,Canada but working in Port Huron,Mi. Posts: 1,771	Re: 1972 Blazer transmission swap? No problems with the transfer case,it's the adapter that goes in between the trans and T/C that's different. the th350 adaptor is on the left,the sm465 adaptor is on the right. here is an article on swapping a manual (SM465) to automatic (TH350) conversion. http://www.geocities.com/spencerhut/...trans_swap.htm __________________ 71 blazer,350SBC,approx.375HP,700R4,factory GM TPI.Dual electric fans,33x12.5x15 ATR on stock suspension. Petrolia,Ontario,Canada but working in Port Huron,MI. See ALL my Blazer pic's HERE Last edited by BobbyK; 01-20-2006 at 01:43 AM.

01-20-2006, 02:34 AM	#3
TX72K5 Junior Member Join Date: Jan 2006 Location: Fort Worth, Texas Posts: 57	Re: 1972 Blazer transmission swap? Thank you for the info. Mike

01-20-2006, 04:09 AM	#4
Gyva Registered User Join Date: Jan 2005 Location: Mountain Home Idaho Posts: 544	Re: 1972 Blazer transmission swap? so if you change out a manual on an old 65 2 wheel drive with an auto TH350 will you be forced to get a new driveline because of the different lengths trannys? something I was wanting to do eventualy. Mike... Last edited by Gyva; 01-20-2006 at 04:09 AM.

01-20-2006, 07:40 AM	#5
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	Re: 1972 Blazer transmission swap? The transfer case that was attached to the SM465 has a 10 spline input, you will need to find a case with a 27 spline input to use behind the TH350 or change the input in the t-case you have. __________________ Tim

01-21-2006, 12:24 PM	#7
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,852	Re: 1972 Blazer transmission swap? Try to find a complete unit:TH350/adaptor/205.It`ll bolt right in and you can sell your complete 4spd unit for a trail-rig. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

01-21-2006, 06:34 PM	#8
ajbirken Registered User Join Date: Nov 2002 Location: raleigh, NC Posts: 60	Re: 1972 Blazer transmission swap? It's pretty funny. I have a TH350 in mine and would love an sm465. __________________ 1971 GMC Jimmy 350/350/205/D60/14bolt on 38's 1984 M1008 CUCV 6.2/TH400/208/D60/14bolt on 36's 1991 W250 5.9/G360/205/D60/D70 on 33's (tow-rig) Lotsa Full Size Jeeps (J10/J20)! Adam

01-22-2006, 08:44 PM	#11
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,852	Re: 1972 Blazer transmission swap? That`s what I was wonderin`.PM that guy to make sure he knows your interest. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

01-23-2006, 01:59 PM	#12
crispy '71 Chevy Blazer Join Date: Jan 2005 Location: San Leandro, CA (near Oakland) Posts: 96	Re: 1972 Blazer transmission swap? i just did the opposite swap... interesting side note, i didn't have to have my drivelines altered at all... i thought for sure that i would have had to __________________ '71 K5 Blazer (new project / daily driver) "If you are not working to improve the situation, you have no business complaining"

01-25-2006, 09:48 AM	#14
TX72K5 Junior Member Join Date: Jan 2006 Location: Fort Worth, Texas Posts: 57	Re: 1972 Blazer transmission swap? Will a 700R4 bolt up to the 1972 transfer case?

01-25-2006, 11:05 AM	#15
BobbyK Registered User Join Date: May 2000 Location: Petrolia,Ontario,Canada but working in Port Huron,Mi. Posts: 1,771	Re: 1972 Blazer transmission swap? With a output shaft modification,yes. __________________ 71 blazer,350SBC,approx.375HP,700R4,factory GM TPI.Dual electric fans,33x12.5x15 ATR on stock suspension. Petrolia,Ontario,Canada but working in Port Huron,MI. See ALL my Blazer pic's HERE

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