# MY6 4 Speed OD Conversion



## dcoydad (Sep 27, 2017)

Hi folks. My 68 is numbers matching, my plan is to shelf the entire drivetrain and replace with daily driver stuff so I'm not worried about tearing up some history. So I started with a factory open rear end geared around 3:23 but hated the one tire fire. I stumbled onto a nodular posi out of a 69 Judge with 3:90s. Fixed the fire but killed the road cruise. Now taching around 4000rpm at 75 on the interstate. I've been looking at options: ruled out the Tremek/TKO because I don't want to modify my floor pan. Considering the new Mcleod 5speed because its advertised as a direct drop in without modifications - but it is expensive... Ran across on old timer who mentioned a possibility and wanted to ask the forums for advice.


Has anyone converted the MY6, 4 speed, OD tranny's from the chevy/gm trucks into their goats? My understanding is the OD 4th gear runs at .74 which is way better than the 1 to 1 on my Muncie. The dimensions look very good too. I understand the tranny is actually a version of the Chrysler A833 and pretty darn tough. Another question is? Do they make conversion plates for the A833 to a BOP bellhousing? The MY6 has been hard to find and I'm still looking --- so if you have one sitting around? The A833s are out there if there is an adapter plate available... Anyone been there done that? Let me know. Thanks


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## PontiacJim (Dec 29, 2012)

dcoydad said:


> Hi folks. My 68 is numbers matching, my plan is to shelf the entire drivetrain and replace with daily driver stuff so I'm not worried about tearing up some history. So I started with a factory open rear end geared around 3:23 but hated the one tire fire. I stumbled onto a nodular posi out of a 69 Judge with 3:90s. Fixed the fire but killed the road cruise. Now taching around 4000rpm at 75 on the interstate. I've been looking at options: ruled out the Tremek/TKO because I don't want to modify my floor pan. Considering the new Mcleod 5speed because its advertised as a direct drop in without modifications - but it is expensive... Ran across on old timer who mentioned a possibility and wanted to ask the forums for advice.
> 
> 
> Has anyone converted the MY6, 4 speed, OD tranny's from the chevy/gm trucks into their goats? My understanding is the OD 4th gear runs at .74 which is way better than the 1 to 1 on my Muncie. The dimensions look very good too. I understand the tranny is actually a version of the Chrysler A833 and pretty darn tough. Another question is? Do they make conversion plates for the A833 to a BOP bellhousing? The MY6 has been hard to find and I'm still looking --- so if you have one sitting around? The A833s are out there if there is an adapter plate available... Anyone been there done that? Let me know. Thanks



I don't think I would do it after reading this thread. This is for a Camaro, but still gives you a very good idea of what you might be getting into - NP440/MY6 Swap Info | NastyZ28.com


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## 11th Indian (Feb 15, 2018)

I am installing a Tremec 5 speed, I was told by the vendor (SilverStar) the the 68 to 72 only may6 need a slight dimple to install. Now the 66 to 67 is another story....


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## dcoydad (Sep 27, 2017)

Update on the Upgrade. Found and installed a MY6. Pretty straight forward conversion. Had to have front bearing retainer turned down and message the shifter mounting bracket. Very pleased with the OD performance now.. I think we are going to trade out the Muncie on my sons 68 firebird with the MY6 next.


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## v8bike (Feb 2, 2020)

dcoydad said:


> Update on the Upgrade. Found and installed a MY6. Pretty straight forward conversion. Had to have front bearing retainer turned down and message the shifter mounting bracket. Very pleased with the OD performance now.. I think we are going to trade out the Muncie on my sons 68 firebird with the MY6 next.


i know this is an old thread, but were you able to use the pontiac bell housing & drill extra holes? did you have the a833 or muncie bolt pattern on the transmission? i have one with the a833 pattern & want to put it behind a 389. thanks ahead dale


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