what 4 speed manual transmission fits on a 1970 455?

[maverick_124]

dude, your epic!!

 

[Oldsmoletick]

I like the MY6 in my El Camino. While officially a truck transmission, it's a variant of the New Process A833 ("Hemi 4-speed") and very durable. The GM version is technically a 4-speed but 4th is an OD, which is nice with a torquey engine like a 455. There are several case styles, both cast iron and aluminum. You would need the traditional style front bolt pattern to use with a Gbody bellhousing. There is also a MY6 specific case also that will not work with it. You may have to machine the front bearing retainer down to Muncie/Saginaw/T10 size too. There are adapters available to bolt a MOPAR A833 to any GM bellhousing. Some info:
http://www.hotrodreference.com/102/mopa ... ar-ratios/

I'm slowly gathering parts to do this swap, lol, so far I have located the required adapter to use a MOPAR A833OD behind a gm bell (ebay), a set of pedals I think will work, hydro set up, and transmission with shifter (haven't picked it up yet though 😳 ). All really I'm lacking is the fly and bellhousing 😀.

 

[Bonnewagon]

That's an awesome set up! With 3.09 first gear and a 3:23 rear you would have 9.98 overall ratio, and then the .71 overdrive would make the 3:23 into a 2.29 rear. Pretty nice driver.

 

[Oldsmoletick]

^Yup 8) I plan on using 3.42's though, which would bring th OD ratio into the 2.49 range for milage sake (I found the .73 OD).... Best part is they are the same length as a th350 and take the same mount so no funky crossmember work .

 

[maverick_124]

thats the only thing im worried about..is the cross member..lol

 

[DRIVEN]

Mine is between a SBC 400 and a 3.08 10 bolt. It's just low enough to tow with and still lets me get about 20mpg. Not really ideal for drag racing due to the wide ratio but makes an excellent driver alternative.

 

[maverick_124]

im probably gonan do 4.10's..but i know nothing about ratios lol i want good MPG, and good speed on the strip

 

[DRIVEN]

Don't get greedy on the rear gears. Running a 4.10 is pretty good with a Muncie or T10, but a little steep for the MY6 or most Saginaws. 10:1 is the generally accepted sweet spot for a street car. Bonnewagon nailed it with the 3.23 suggestion. Multiply the rear ratio X first gear ratio. Too high a number will feel like a farm truck granny gear, too low will be a dog off the line. Also, try playing with this for a few minutes:
http://www.angelfire.com/fl/procrastination/rear.html

 

[maverick_124]

well I was thinking about a T10

 

[Bonnewagon]

Early T-10's were not very strong. They were replaced by the Muncie. It is VERY easy to be duped into buying one of these turds as they look like the newer ones. Watch your casting numbers! Look for a Super T-10 from the mid 70's on, but watch out for the 80's "F" body models, the shifter mounts on the passenger side. The shifter is a POS but the trans is good. Look for the fine 26 spline output shaft. ST-10's came with various first gears, all the way up to 3:42.