Converting 3 speed manual to auto question.

[Bjj_junkie]

Hello everyone, I'd like to see if I can get a clearer picture of how to swap out a 3 speed manual transmission to an automatic one. Please excuse my lack of auto mechanics knowledge. I have spoken to people and they say it can be done but I have no idea what's the process and what else I need to get besides the transmission.

I recently bought a 72 stepside with a 250 and a 3 speed. I'm pretty sure I'm sticking with the 250 but the transmission has to be changed since I don't drive stick. What throws me off is the floor shifter that's there now. Does that need to be removed and plugged up and get a steering column with auto shifter or what? Like I said excuse the complete lack of knowledge but I'm new to this and my main guy that's gonna help me on this is out of town for a few months

Thanks for your time

[c3006]

Yes you will want to fill that hole in the floorboard up,take out the clutch pedal,find a steering column for your automatic and find a radiator with the cooling capabilities along with the transmission fluid lines to it.I guess you could go with a power glide or a turbo 350 deepening on your preference. It's not that hard to do and will make a great learning project. Good luck and have fun..

[TheSeeker]

If you do not want the column shift there are kits to use floor shifters with auto transmissions. You will need to move the cross member back some I believe as the 250/3 speeds had only 1 and it is farther forward. There has got to be a writeup somewhere in the FAQ section

[hugger6933]

You are also gonna need a rear crossmember as the 3oot's don't have them, they have a center mount. it is mounted to the frame on both sides holding the motor and trans. Also your gonna need a flywheel for the auto but it is no biggie. All of this stuff can be found fairly easily and reasonably inexpensive. I have a 70 model truck with the 3oot trans and I'm doing a T-5 swap and that will be different [just a little] and have the much needed overdrive ratio[gas today is $3.56 in my town] Jim

[michael bustamante]

Ok heres a quick run by.. get an auto trans crossmember. Easy to find and always for sale here. Get a floor shifter. New not used as all the little parts always seem to be missing. When you get a tranny be sure to get the torque converter with flywheel. And the yoke at the tail end of the trans. Cut out or drill out the rivits holding the 3 ott tranny crossmember. Disconnect driveline and remove bolts and stuff conncting trans to engine. Remove trans. Attatch new flywheel to engine. Measure and position and drill holes in frame for the new crossmember where it needs to go. Once you see where the auto trans connects itll show you where to munt the crossmember on the frame. Dont bolt it on yet though. Make sure converter is sitting properly in the trans ( 2clicks)Put trans on a jack. (Tranny jack works best) and lift trans to where it needs to go. Bolt the t converter to the flywheel and use thread locker! Slide crossmember in place and bolt.
Trans is in. Now remove clutch pedal. ( springs lever etc) youll most likely have to cut the shaft feeding tjru the pedal assy. Install new floor shifter as per instructions. Attatch cable to carb. For turbo 350. Take your yoke and driveshaft, measure your shaft to have a portion cut off and take to a driveline shop and havenew u joints andcarrier bearing installed. Install driveline. Put new fluid. Install dipstick first. And that should do it. Have fun and take your time.

[71sixgun]

What about the low hump in the floor? Will an auto trans clear that?

[michael bustamante]

Hmm i dont know. Ive only done tall humps. Get a hold of tx firefighter. Thst guys a whiz on our trucks