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Th350 transmissions

 
burniased
I love my Chevy Chevette!
Posts: 1
Joined: 05/14
Posted: 05/25/14 06:09 PM

I have a 1981 chevy c10 shortbed it has a 350 sb (supposably out of a 77 Nova) and  a th350 trany with a 9" rear. The trany went out the other day and I ended up buying a th350 with a 6" rear out of a 75 Pontiac firebird with a 400 sb not knowing that they were different! We'll I ended up buying an adapter to bolt the new trany to my sb ... Basically I need to know "how to" and "what I need to do to have this connected to be able to drive???"  

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wayne712222
My first time was in a Chevy
Posts: 245
Joined: 10/13
Posted: 05/26/14 10:30 PM

an 81 chevy truck TH350 is probably a LOCK UP MODEL TH350C.. depending on where it was first sold..  if the transmission is out of a 77 nova.. it might not be a LOCK up..  

it would probably be cheeper at this point.. to get somebody to rebuild the original TH350...   they are not that hard to rebuild..
http://www.circletrack.com/drivetraintech/ctrp_0809_th350_transmission_build/viewall.html


i am taking that the firebird transmission needs the adaptor plate. as the bellhousing has POINTY ears on top instead of the nice single chevy point..

you will need to find a proper torque converter.. as the pontiac unit will not work with a chevy flywheel. but that's not a huge issue..

you may be able to use either converter.. but.. chevys usually use a tab with a nut and bolt.. BOP converters use three mounting bosses that are drilled and tapped..

to tell if your torque converter is a NON LOCK UP or a LOCK up type..

a NON LOCK up converter for the TH350.. has a rounded side near the 3 mounting tabs or mounting lugs..  

a LOCK up converter will have 3 mounting lugs that are drilled and tapped..  and it will have a stepped face near the mounting lugs..

read the article i linked on the TH350 build..  there are videos and booklets on this.. and many  parts stores can order the rebuilding kit.. but you are better off usually.. if you want to do the rebuild..  order it from a transmission PARTS SUPPLIER.. these are companies that sell directly to the transmission shop.. ..

to use the 6 inch tail housing.  you will need a longer drive shaft .. i don't recall if you have to slide the cross member forward..probably not.

and don't throw out the 9" tail housing TH350..  and don't turn it in for a core..

that is the EXACT transmission that will bolt in for somebody who wants to replace the 700R4...  it is almost an exact fit.. the gear shift position is slightly off..  the 9" tail housing versions are popular for that exact reason..  

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