'67 250 w/3 speed convert to auto trans...???

[veedubshafer]

So at some point I'd like to swap in an automatic Behind my 250 C10. What transmission would be a good choice? What are some of the not so obvious things I need to know and/or buy? Thanks for any help.

[trac209]

Turbo 350 would be my choice.

[Scottcoda]

You will find that across the web on many diffrent sites that this debate of TH350 vs TH400 rages on.. from my research most people will say that the TH400 is heavier and bulletproof, that it is a better tranny to have if you have big block or plan on breaking 500hp.. with your 250CI the 350 would be perfect as it is said it should not take as much to turn it.
when I found my GMC I was a little disspointed that it did not have a V-8 but very happy that it had a TH400... I now love my 250CI and the improvments I have made to it and glad it is mated up to a bulletproof tranny.
If I was you I would see what I can find locally and if you can grab a nice well taken care of tranny for a good price, thats the one I would take, whether it be a TH350 or a TH400

[Longhorn 70]

200 4r would be my choice depending on tail gears. You'll get out of the hole better and cruise better as well.

[trac209]

Originally Posted by Longhorn 70

200 4r would be my choice depending on tail gears. You'll get out of the hole better and cruise better as well.

The only reason I did not recomend an od trans is that idk if there is a way to make the very important tv cable operate correctly with the inline 6. If there is I would use that for reasons you stated as well.

[veedubshafer]

So with a TH350 you don't need a kick down cable? What about crossmember and drive shaft length. I currently have an SM420.

[trac209]

Originally Posted by veedubshafer

So with a TH350 you don't need a kick down cable? What about crossmember and drive shaft length. I currently have an SM420.

Yes and no. You can run without one but you have to shift down for passing etc. also the turbo 350 was used behind inline sixes so they have the correct bracket for the cable. A 700r has a tv cable that is very sensitive to adjust and controls the way the trans shifts by altering line pressure.

[veedubshafer]

Ok I got ya. I'd put a lokar or similar floor shifter on it anyway so I could live with knocking it down to pass. Or if that didn't go well I could hook up the cable. I dealt with a TV cable on a jeep so I know how sensitive they are.

[factorystock]

More than likely, you have the standard 3.73 ratio, so an overdriveauto is probably most desireable trans in todays world of higher speed limits. Unfortunately, there is no TV kit for auto overdrives engineered precisely for the 6 cyl. available. When will the aftermarket suppliers help us out on this? As far as I know, you have to fab one up on your own. Its possible someone on a NOVA site came up with a system, the majority of early Novas were built with 6 cyl engines.

[veedubshafer]

I don't think over drive is a necessity for me. What am I looking at otherwise? Crossmember, driveshaft etc if I go with a turbo 350?

[michael bustamante]

Youre going to need a good grinder and cut off wheel and a bfh to take out the manual tranny crossmember. Thats where im at now on my 67

[veedubshafer]

Originally Posted by michael bustamante

Youre going to need a good grinder and cut off wheel and a bfh to take out the manual tranny crossmember. Thats where im at now on my 67

Ok so there's a different crossmember. I figured that but wasn't certain.