# 4 speed conversion



## mbspeed (Sep 25, 2012)

Hi all I got a 67 GTO THM 400 wanted to put in a manual 4 speed in I can get all the manual parts from a 69 Chevy a body my ?s will all the parts work I know I will need a new bell housing and z bar any info will help


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## Bensjammin66 (May 12, 2009)

Fun times! 4 speeds drop right in with very little effort. 

-TH350 and Muncies share the same driveshaft but the TH400 is a tad shorter i believe due to a longer tail shaft. Try to land a TH350 shaft or measure once the muncies in and then have yours modified or use your buddies 69 shaft as a donor to cut up and extend/reduce the length. I think the trans mount is the same for all 3 but dont quote me. TH350 and Muncie's share the same trans mount / cross member for sure though. ( not too knowledable on the 400's I know, sorry ) 

As far as the bellcrank goes when I did my TKO600 conversion i scored everything off ebay cheap. Bushings, zbar, block stud and the frame tab that needs welded on all for like $65. The pedal swingset I got on ebay too, maybe $75? I made my own pushrod out of steel stock and heim joints though. 

You will need to chop the goats floor just a lil bit to weld in a floor riser where the shiter comes through too. Not a big deal at all. Cut off wheel and a mig. Done. 

What else did you need to know?


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## geeteeohguy (Feb 2, 2008)

You will need a 4 speed with a Pontiac tailhousing. The speedometer cable needs to be on the driver's side of the gearbox. Other than that, same parts. Chevy had Muncie shifters and Pontiac used the superior Hurst units. I would use a Hurst unit.


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## ALKYGTO (Mar 29, 2010)

^What these guys said except you never want to _lengthen_ a driveshaft.


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## mbspeed (Sep 25, 2012)

cool thanks guys the 69 chevelle 396 BB sat for over 27 years under tree not covered and had about 2 '' water on floor never saw a car rotted as bad as this 1 i can not see parts i need yet but i pray i can blast and recoat them ......dam i wish i could go with the TKO 600 I priced that pack it was like 6 gs i wish


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## Bensjammin66 (May 12, 2009)

ALKYGTO said:


> ^What these guys said except you never want to _lengthen_ a driveshaft.


yah that does sound like a bad idea, in that case should he just start with the th350 shaft? Someones bound to need his th400 shaft on craigslist or something. 

One other thing to check once your auto is out is to make sure your crank is drilled for a pilot bushing. Should be, most poncho cranks are I believe.


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## Bensjammin66 (May 12, 2009)

mbspeed said:


> cool thanks guys the 69 chevelle 396 BB sat for over 27 years under tree not covered and had about 2 '' water on floor never saw a car rotted as bad as this 1 i can not see parts i need yet but i pray i can blast and recoat them ......dam i wish i could go with the TKO 600 I priced that pack it was like 6 gs i wish


TKO600 for $6,000?!? I'll sell ya mine for $4,000 then! lol! All joking aside I think i paid $2,295 for my TKO from Summit Racing. Another $600-$700 or so for a steel flywheel and clutch. That is serious cash though considering rebuilt M21s are like $800-$1000 around here. I tell ya what though man, with 3.73s the 455 is turning 2100rpm @ 70mph and i'd have it no other way. If I could do it all over again id start with a T56 6 speed from a vette or camaro.


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## geeteeohguy (Feb 2, 2008)

27 years under a tree outside is an excellent way to turn a classic and valuable car into scrap or, at best, a parts car. I see a lot of this, and find it very upsetting. And the kicker is, the car is NEVER for sale.


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## ALKYGTO (Mar 29, 2010)

Bensjammin66 said:


> TKO600 for $6,000?!? I'll sell ya mine for $4,000 then! lol! All joking aside I think i paid $2,295 for my TKO from Summit Racing. Another $600-$700 or so for a steel flywheel and clutch. That is serious cash though considering rebuilt M21s are like $800-$1000 around here. I tell ya what though man, with 3.73s the 455 is turning 2100rpm @ 70mph and i'd have it no other way. If I could do it all over again id start with a T56 6 speed from a vette or Camaro.


:agree ^ I paid about $2500 for my kit from Kiesler that came with the floor hump and upgraded shifter . 

My car with 4:11's turns about 2300 at 70+ with 29" tall tires. 

Bensjammin66; to me a 6 speed is unnecessary as no real need for two overdrives and the extra bulk and weight of the T-56. And it is no stronger than the TKO. :cheers


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## ALKYGTO (Mar 29, 2010)

Bensjammin66 said:


> yah that does sound like a bad idea, in that case should he just start with the th350 shaft? Someones bound to need his th400 shaft on craigslist or something.
> 
> One other thing to check once your auto is out is to make sure your crank is drilled for a pilot bushing. Should be, most poncho cranks are I believe.


Yeah, I would say start with a th350 shaft and save the other, trade it or sell it intact.


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## mbspeed (Sep 25, 2012)

Bensjammin66 said:


> TKO600 for $6,000?!? I'll sell ya mine for $4,000 then! lol! All joking aside I think i paid $2,295 for my TKO from Summit Racing. Another $600-$700 or so for a steel flywheel and clutch. That is serious cash though considering rebuilt M21s are like $800-$1000 around here. I tell ya what though man, with 3.73s the 455 is turning 2100rpm @ 70mph and i'd have it no other way. If I could do it all over again id start with a T56 6 speed from a vette or camaro.


thats awesome a TKO 600 is better then a t56 no ???? the kit i priced was a full conversion kit no cutting no mods and i think also i got the top part of console i have done a manual conversion on a few 3rd gen F bodys years ago and i remember what a pita it is not having all parts in a kit form


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