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**70STOVEBOLT** · 11-14-2019, 09:10 PM

Straight six trucks with 250 and 3OTT came standard with 3.73 gears. They work well for hauling with the big block, but you will definitely need an overdrive trans for highway cruising. I converted from a 250 to a 402 and mine runs about 2800 rpm at 60 with the 402 and TH400 and the original 3.73 gears, with 29.5” tires. If I drive it with a light right foot I can get about 12.5-13 mpg

11-14-2019, 09:10 PM	#5
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,212	Re: 1970 C10 rear end questions Straight six trucks with 250 and 3OTT came standard with 3.73 gears. They work well for hauling with the big block, but you will definitely need an overdrive trans for highway cruising. I converted from a 250 to a 402 and mine runs about 2800 rpm at 60 with the 402 and TH400 and the original 3.73 gears, with 29.5” tires. If I drive it with a light right foot I can get about 12.5-13 mpg __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Power windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear Last edited by 70STOVEBOLT; 11-18-2019 at 04:47 PM.