4 speed transmission question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1burb2many · 02-14-2012, 08:28 PM

can someone tell me if the transmission is the same for a 1963 GMC v6 and a 1961 Chevy Apache straight 6? they are both 4 speed on the floor trucks.

Wrenchbender Ret · 02-14-2012, 11:36 PM

Probably not. GMC mostly used New Process trans. in those years. They are easily ID 'd as the NP has an aluminum cover.

markeb01 · 02-15-2012, 01:36 AM

There is a possibility they could both be SM420’s. My 1960 GMC had an SM420 when purchased, but the truck originally was produced with a 3 speed on the column.

Here’s a link explaining all the details of the SM420, so you’ll have something to check it against.

http://www.novak-adapt.com/knowledge/sm420.htm

02-14-2012, 08:28 PM	#1
1burb2many Registered User Join Date: Jan 2012 Location: San Ramon, ca Posts: 7	4 speed transmission question can someone tell me if the transmission is the same for a 1963 GMC v6 and a 1961 Chevy Apache straight 6? they are both 4 speed on the floor trucks.

02-14-2012, 11:36 PM	#2
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: 4 speed transmission question Probably not. GMC mostly used New Process trans. in those years. They are easily ID 'd as the NP has an aluminum cover.

02-15-2012, 01:36 AM	#3
markeb01 Senior Enthusiast Join Date: Feb 2007 Location: Spokane Valley, WA Posts: 8,356	Re: 4 speed transmission question There is a possibility they could both be SM420’s. My 1960 GMC had an SM420 when purchased, but the truck originally was produced with a 3 speed on the column. Here’s a link explaining all the details of the SM420, so you’ll have something to check it against. http://www.novak-adapt.com/knowledge/sm420.htm



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