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I'm not trying to rod my 63' 3/4 ton Chevy truck but...
having a mildly built 350 backed w/ a 4 spd graany low and a farmer's rear end is like putting a turbo on a tricycle. Is there a differential I can put in it w/out changing the whole housing or an overdrive gear set for the trans without adding a aux. overdrive unit? I love my 4 speed but I'm close to putting in a rebuilt th400 w/ a one piece driveshaft. Please give me some good news. Thanx.
 

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Most people who have a truck like yours (I have a 76 F-250 with a granny 1st gear 4 speed) don't use 1st gear. They just start out in second.

Your rear end gearing has nothing to do with your granny gear trans. Your trans has a 1:1 final drive ratio and so will any other 4 speed that isn't an overdrive trans so changing the rear gears won't effect the granny enough to even notice. The only thing you can do is swap out the granny trans for another one. Granny transmissions were an option with these old trucks so just do a little research and you'll find out which regular 4 speed was available for your truck and just swap one of those in. That will be the easiest way to do it. If you can't find one you can probably use most any of the car 4 speeds but you might have to change the rear trans mount and modify the drive shaft length that way.

Good luck.
 

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Centerline said:
Most people who have a truck like yours (I have a 76 F-250 with a granny 1st gear 4 speed) don't use 1st gear. They just start out in second.

Your rear end gearing has nothing to do with your granny gear trans. Your trans has a 1:1 final drive ratio and so will any other 4 speed that isn't an overdrive trans so changing the rear gears won't effect the granny enough to even notice. The only thing you can do is swap out the granny trans for another one. Granny transmissions were an option with these old trucks so just do a little research and you'll find out which regular 4 speed was available for your truck and just swap one of those in. That will be the easiest way to do it. If you can't find one you can probably use most any of the car 4 speeds but you might have to change the rear trans mount and modify the drive shaft length that way.

Good luck.
I think the only 4spd you could get in that truck had a granny 1st gear. I have never seen one anyother way and I have seen a ton of them.The reverse is also a granny.
 

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DougMN said:
I think the only 4spd you could get in that truck had a granny 1st gear. I have never seen one anyother way and I have seen a ton of them.The reverse is also a granny.
I was going by my Ford. Ford offered two different trans one with a granny and one without. Doesn't make sense that GM wouldn't give owners a choice, but then I'm no Chevy expert. Guess his only option is to find a "car" 4 speed that will work.
 

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yes the only 4 speed manual in these were the top loaders

there was the warner and NP 435 and NP 435Cr and the CH465(some ppl call them SM465)

and in a couple years there was another top loader 4 speed available in these trucks i forgot what model, but most have either the 465 or one of the 435's

and the SM420 was '67 and older, no 465 trans before 68, 420 reverse is on driver side instead of the pass side like the 465 was



the 435 was not a granny first ratio tranny and the warner i forgot, i have all the original gm info on these i can scan lists, the models of trannies and their ratios, for 67-72 trucks

there was an aluminum 4 speed manual side loader available for a couple years in the later years trucks bbut very uncommon/rare
 

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also, if this is a 3/4 ton 4X4, with a 4spd, it likely has 4.56 gears, that was standard for the 3/4 ton 4X4's, had to get it special to have diffrent.

The SM420, is a Muncie transmission.
 
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