76 Custom Deluxe tranny swap..

[jmitch333]

Hey guys, Im new to the forum and I could not find an answer to my specific question anywhere on this forum upon searching. I just bought my first truck, a 76 Chevy Custom Deluxe Longbed with the 250 straight six engine and 3 speed manual tranny (previous owner converted from the column to the floor). To my understanding, everything is stock. What I am wanting to do is swap out that manual tranny for an automatic tranny but I dont know what will work and what vehicles I could pull one off of that'll work with the 250 and what other parts I would need. Any suggestions?? Thanks in advance.

[N2TRUX]

Welcome to the forum jmitch333. You should be able to put a TH350 or 700r4 behind your six. You can piece it together, or find a donor truck to get everything you need.

[old Rusty C10]

you could put a overdrive behind it but you would need to get the wiring for it too

[leegrady]

Some of the things to consider when making such a conversion is: other than the obvious,
Radiator will need to be changed with one with a trans cooler.
Rear end gear ratio varies between a manual and an automatic, and propeller shaft length.
Automatic overdrive trans. use computers, and sensors to operate shifts, and lockup converters.
Neutral safety switch.
Automatic transmission brake pedal, (it's larger).

I would recommend a thm350 or thm400, non-computer controlled.