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View Full Version : Auto trans to put behind 401?


Mike Caldwell
November 5th, 2021, 01:03 AM
I've had this engine (it came out of "New Idea" harvester) for several years and finally am going to get the project going.

While I'm getting the engine running I'm planning for what to put it in -- debating between '49 Willys PU and building a 'glass Model A PU.

Either way this old body tells me it's time to get an automatic but the new ones have too many electronic connections that don't exist on the big V-6.

So what are my choices?? What's out there that will work without too much custom equipment???

jbgroby
November 5th, 2021, 02:01 PM
Mike,

I just did a swap behind my 305V-6 this past summer and have a full tutorial written I also posted it on the BB as well. You can find it here
https://6066gmcclub.com/showthread.php?t=50844

I had an old and worn out 4 speed Hydramatic, the rebuild cost were $3200+ and I still would NOT have overdrive. I put in a GM 700R4 (non-electronic 4 speed with overdrive). The 305 REALY LOVES THIS! I attached a p[ic of the truck doing 80 MPH and only turning 1850 rpm (I have 3.23 danna 44 rear gears).

To go forward, you will need to do 1 of 2 options. Find an factory original automatic adaptor setup (pictures attached), you will need the flywheel, spacers, flex plate and adaptor ring (they are out there , but you got to really search) or you can simply buy one from Bendtsend Transmission Adaptor for approx. $1200. I found my factory unit for $400, plus shipping.

The swap is simply and NO ELECTRONICS. However, you will need to purchase the Bowtie Overdrive kickdown kit ($200) and Carb adaptor plate/Wire accelerator set up, you will no longer be able to use the bell crank pedal set up as the adaptor plate will interfere with the movement.

Its a super simple swap and I did it myself with a friends help with NO experience. You will most probably want to work from lift to make it easy as we did.

Mike Caldwell
November 13th, 2021, 03:25 AM
problem is that 700R4 is rated for 350 ft lbs and 401 is rated at 370 more gears would also be nice.

jbgroby
December 8th, 2021, 11:27 AM
Sorry for the late reply, I just saw your post. I too was initially worried about the torque, until it was explained that unless you're trying to do burnout and such the 700r4 is great.

Mike Caldwell
December 8th, 2021, 09:46 PM
Thanks for the information. May solve my (first) problem! Now on to the next!