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#1 |
Registered User
Join Date: Oct 2017
Location: Kamloops BC, Canada
Posts: 20
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What transmission do I have? 72 Sierra Grande
Trying to find a replacement tranny, but I’m having a hard time figuring out which one to search for. 72 GMC Sierra Grande with the 350 engine. It’s an automatic and it leaks like crazy! Probably 4 litres of atf fluid on the driveway. The option # on my sticker says M49-Turbo Hydra-Matic, but I know that could mean it’s the TH350 or TH400. Where do I need to look to figure this out?
Thanks, The new guy |
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#2 |
Registered User
Join Date: Jul 2015
Location: Sedalia Mo.
Posts: 1,131
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Re: What transmission do I have? 72 Sierra Grande
The TH350 has a square or rectangular pan with a bit of one corner missing while the 400 has a funky shaped one. I can't really explain it's shape so look it up. Part of it kinda looks like the lower half of Texas. I believe the vacuum modulator on the 350 is on the right front while the 400 has it on the right rear. The 350 has a kickdown, cable, the 400 does not, it has an electrical swicth.
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He who is without oil shall throw the first rod. Compressions 8.7:1 1972 C10 1976 C10 (parts truck) 1985 K20 |
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#3 | |
Registered User
Join Date: Oct 2017
Location: Kamloops BC, Canada
Posts: 20
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Re: What transmission do I have? 72 Sierra Grande
Quote:
On another note have you ever seen an extreme leak from one of these? |
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#4 |
Registered User
![]() Join Date: Oct 2011
Location: Victoria, B.C
Posts: 3,794
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Re: What transmission do I have? 72 Sierra Grande
As Sick471 mentioned the TH350 has a 45 degree scallop out of the rear corner and it is largely square in shape otherwise.
The TH400 is clearly longer than it is wide and the TH400 has a 'bump' out on one side defeating the rectangular shape in the rear area....basically the TH400 looks a bit like a race car circuit with only a couple of square corners I think. Coley
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....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500 |
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#5 |
Registered User
Join Date: May 2016
Location: Waverly, NE
Posts: 334
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Re: What transmission do I have? 72 Sierra Grande
They ALL seem to leak from one place or another, but that one looks pretty slimy. If it is just generally tired and leaky why not have it rebuilt instead of buying a new one? Unless you want to upgrade to a more modern overdrive transmission or something. One thing to note, the truck TH350s are different than the car TH350s, the truck versions have one or two more clutch packs than the car versions.
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1965 Malibu SS L79 Restoration Page 1965 Two-Door Wagon Project Progress Page 2006 Pontiac GTO Preservation Project Rich Cummings |
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#6 | |
Registered User
Join Date: Oct 2017
Location: Kamloops BC, Canada
Posts: 20
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Re: What transmission do I have? 72 Sierra Grande
Quote:
Thank you for the information on the differences between the car and truck though, I will definitely use that. |
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#7 |
Registered User
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,177
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Re: What transmission do I have? 72 Sierra Grande
Looks like the dipstick o-ring side leaking. Also the pans can get bent up and leak. I had to use 2 gaskets and "the right stuff" to seal up one once.
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"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
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#8 |
Registered User
Join Date: Jan 2011
Location: Chattanooga, TN
Posts: 2,149
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Re: What transmission do I have? 72 Sierra Grande
A good shop should be able to fix that. The TH350 is a pretty simple transmission.
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'83 K20-TPI '73 C10 '79 C10-ex-diesel(SOLD) '07 Tahoe(Son driving) '14 Suburban-DD '71 C10-current project |
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#9 |
Registered User
![]() Join Date: Nov 2006
Location: KINGSPORT,TN.
Posts: 3,035
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Re: What transmission do I have? 72 Sierra Grande
yep, pull it and take to trans shop
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I BELIEVE IN JOHN 3:16 |
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Tags |
350, automatic, m49, sierra grande, transmission |
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