The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 1985 Chevy c60 ramp truck with a 1970 454, early sm465, & 2 speed Rearend????

66Submarine · 06-06-2013, 10:12 PM

I'm not an expert on anything, much less the "heavies". But, if you already have the two speed rear I think you probably already have 6.40/8.72 ratios, which were pretty much standard. The low range is a planetary reduction of the high/direct range, not another gear set.

You might could find an axle out of a diesel truck with ratios like you like, given that a diesel rear will be designed for lower engine speeds. Or you could look at finding an overdrive five speed trans out of another big truck. You could also consider swapping out the thirsty BBC for a smaller 350 or something if you don't need all the power. You'll still be screaming along at 3,500+ going 65, but you should use less fuel doing so.

Hope this helps.

06-06-2013, 10:12 PM	#6
66Submarine Registered User Join Date: Sep 2012 Location: Dallas, GA Posts: 1,497	Re: 1985 Chevy c60 ramp truck with a 1970 454, early sm465, & 2 speed Rearend???? I'm not an expert on anything, much less the "heavies". But, if you already have the two speed rear I think you probably already have 6.40/8.72 ratios, which were pretty much standard. The low range is a planetary reduction of the high/direct range, not another gear set. You might could find an axle out of a diesel truck with ratios like you like, given that a diesel rear will be designed for lower engine speeds. Or you could look at finding an overdrive five speed trans out of another big truck. You could also consider swapping out the thirsty BBC for a smaller 350 or something if you don't need all the power. You'll still be screaming along at 3,500+ going 65, but you should use less fuel doing so. Hope this helps.