sm-420 swap question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

thebeast61 · 01-29-2011, 05:10 AM

I did not find a thread covering this. I have a 61 gmc with the 305 and sm-420. I was thinking about swapping out the tranny. I was wondering if there are any trannys that i can swap to with minimal modifications. I would rather a bolt on. I just dont need the granny gear.
Also was wondering if putting a different tranny would improve the gas mileage.
I am having to rebuild my 420 and the parts are hard to find and expensive and would like to go with something more common.
Thanks for your help.

01-29-2011, 05:10 AM	#1
thebeast61 Registered User Join Date: Nov 2010 Location: texas city, texas Posts: 66	sm-420 swap question I did not find a thread covering this. I have a 61 gmc with the 305 and sm-420. I was thinking about swapping out the tranny. I was wondering if there are any trannys that i can swap to with minimal modifications. I would rather a bolt on. I just dont need the granny gear. Also was wondering if putting a different tranny would improve the gas mileage. I am having to rebuild my 420 and the parts are hard to find and expensive and would like to go with something more common. Thanks for your help.



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