The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Help- 71 granny 4 speed to saginaw 4 speed

AcampoDave · 03-03-2021, 12:52 AM

Are there rings etched into the input shaft of the Saginaw? If so how many? That will tell you the gear spread

No lines on the input shaft- First 2.84, Second 2.01, Third 1.34, Fourth, 1.00

1 Line- First 2.54, Second 1.84, Third 1.44, Fourth, 1.00

Much less common 2 Line- First 3.11, Second 2.20, Third 1.47, Fourth, 1.00

3 Line- First 3.50, Second 2.46, Third 1.65, Fourth, 1.00

I used to run a 3 line and the spread was so wide that I could roll a 2.76 rear end gear with no problems. It made 4th a bit like an overdrive however, with freeway speeds coming in around 2000-2200 rpm. Be great if you had one that suits your diff gears.

03-03-2021, 12:52 AM	#9
AcampoDave Registered User Join Date: Feb 2013 Location: central California Posts: 2,730	Re: Help- 71 granny 4 speed to saginaw 4 speed Are there rings etched into the input shaft of the Saginaw? If so how many? That will tell you the gear spread No lines on the input shaft- First 2.84, Second 2.01, Third 1.34, Fourth, 1.00 1 Line- First 2.54, Second 1.84, Third 1.44, Fourth, 1.00 Much less common 2 Line- First 3.11, Second 2.20, Third 1.47, Fourth, 1.00 3 Line- First 3.50, Second 2.46, Third 1.65, Fourth, 1.00 I used to run a 3 line and the spread was so wide that I could roll a 2.76 rear end gear with no problems. It made 4th a bit like an overdrive however, with freeway speeds coming in around 2000-2200 rpm. Be great if you had one that suits your diff gears. Last edited by AcampoDave; 03-03-2021 at 01:01 AM.