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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: Monkeyman73 on August 19, 2010, 08:54:42 pm

Title: 3 speed to automatic swap
Post by: Monkeyman73 on August 19, 2010, 08:54:42 pm
I have a 73 C10 with a 3speed on the column and I would like to know if I have to cut floorboard to make room for the automatic , are there any tricks ?
Thanks..
Title: Re: 3 speed to automatic swap
Post by: beastie_3 on August 19, 2010, 09:14:29 pm
I think the high hump floors were only for 4wd and/or manual transmission (floor shift), so you will be ok.
Title: Re: 3 speed to automatic swap
Post by: Swims350 on August 19, 2010, 09:44:12 pm
no,


 autos had low hump and stick shifts if not all then floor shifts had high humps like 4x4's as mentioned already.
Title: Re: 3 speed to automatic swap
Post by: beastie_3 on August 19, 2010, 09:59:14 pm
"no autos" OR "no, autos" ??
Title: Re: 3 speed to automatic swap
Post by: Swims350 on August 19, 2010, 10:04:57 pm
eehh my bad
Title: Re: 3 speed to automatic swap
Post by: beastie_3 on August 19, 2010, 10:06:15 pm
I wasnt sure if you were replying to the OP or correcting me. Just had to ask.
Title: Re: 3 speed to automatic swap
Post by: Swims350 on August 20, 2010, 10:13:46 am
not a prob. man didn't realize how that one turned out LOL. The No was for him on cutting floors.
Title: Re: 3 speed to automatic swap
Post by: bake74 on August 20, 2010, 12:25:23 pm
  Monkeyman, I assume you had an automatic standard in your 73 because of the 3-on-the-tree.  Are you changing to a different automatic transmission, or is your question, you want to move your shifter from the steering column to the floor and what modifications if any you will have to perform?
Title: Re: 3 speed to automatic swap
Post by: bake74 on August 20, 2010, 12:26:59 pm
  Wow, just remebered some of these trucks came manual with shifter on column, sorry my bad.
Title: Re: 3 speed to automatic swap
Post by: Swims350 on August 20, 2010, 12:41:53 pm
yea that was exactly what I assumed he meant by 3 on the tree a speed standard shift and he wants an auto.

another fyi had a 76 had 3 on the tree floor conversion is easy to do and cheap,

a saginaw 4 speed or maybe another like muncie is the same length, same driveshaft and same mount to put in place of the 3 speed stick from stock, and a th350 short tail 6 inch tailshaft is the exact same bolts up in place and uses the same mount and crossmember and location. Shiftiing it is gonna require an auto column swap or a floor shifter for an auto. If you do a column you you'll need all the linkage of course to make it work. You are also gonna need an auto radiator or a large aux. trans cooler for an auto and cooler lines. If you go with a th350 or 400 which has a vacuum modulator you're gonna need to run a manifold vac. source to it, be it a tee into something like the brake booster line or right in the intake. There is a kicdown cable on the th350 and may require a bracket to mount it to the engine depending on what it has on it, stock or universal brackets can be found cheap. A 700r4 of course has the tv cable same deal, needs bracket to mount, th400 has eletronic kickdown switch mounted by the gas pedal need that or a aftermarket kit to hook it up and make it work, or pull the shifter down a gear to pass lol. 700r4 and th400 are gonna need some sort of driveshaft, crossmember and mount reconfigure/movement/fabrication or modification. A 700 is also gonna need a lockup kit for the torque convertor same as a th350c would need.

I hope that helps anyone else who might want to do this or maybe the OP, but I think he already knows or has what he needs since he only asked about the floor.
Title: Re: 3 speed to automatic swap
Post by: Monkeyman73 on August 20, 2010, 09:19:40 pm
Thank you guys for all the usefull info,, Its what i really needed to make  plans for the swap