[Mrwood]

Can anyone give me info on these numbers i took off my s10 rear end. I need to know what year it is and what gears came in it. I have to go to a higher gear ratio as my engine is reving to high at 60mph. The rear end came from a 4 wheel drive s10. Thanks for any help on this as i need to get new gears put in real soon. Thanks. Here are the numbers-- KUR-C-205-1

[sqzbox]

Your going to have the gears changed anyway so why not remove the cover and devide the amount of ring gear teeth by the number of pinion teeth?
The ratio should be stamped on the edge of the ring gear also.

[big gear head]

Try here. http://www.s10forum.com/forum/transmission-and-rearend/

[Mrwood]

Ok i still dont know what my gear ratio is yet, but im running a 250 six cyl, 3 speed trany, so what do you all think would be a good gear ratio for driving in the 70 to 75mph range. Like i said my engine is just winding up to high with whatever i have now. I dont know much about rear gear combos, so i need good advice on this. You all have never let me down before, and now that i have to have someone else do my work on it, i need help. I have one show i want to go to next year and its 250 miles away. I want to go to this one show before i lose my last eye. My brother has to drive me everywhere now, as i cant see good enough to drive anymore, but i have spent 7 years building my 48 chevy and i just cant give up yet. Thanks again my friends.

[big gear head]

Chances are you have a 3.73 or 3.42 right now. To run the RPMs that you want to run you need something around a 3.08 or 2.73. This is going to make it hard to take off with the 3 speed. An overdrive woudl be better and just keep the rear end that you have now. If you want to keep the 3 speed then I recommend changing the complete rear end. To go from a 3.73 or 3.42 to a 3.08 or 2.73 you will have to change the gears and differential. The 7.5 10 bolt uses the 2 series for the 2.73 and 3.08 and the 3 series for the 3.42 and 3.73. This will be a lot of work and changing the complete rear end will be easier.

[Mrwood]

Thanks for the info. i will get the gears changed now. Thanks again.

[Mrwood]

Would it help to just put a chevy 5 speed trans in, and will it bolt in place of my 3 speed. Just a thought .

[sqzbox]

A 5 speed would be a good choice with the gears you have now.
You have to consider that with the 5 speed you'll need a new floor shifter and relocate or change the cross member location. A few other things would be clutch linkage compatibility, back up lights, and I'm sure an issue with the tranny to drive shaft yoke.
It might be easier to just swap out a different rear axle with the ratio you want. 3:08's would still take off ok with lower hwy rpm's.

I'm with big gear head on this one. One tip is geat a can of PB Blaster and a 3ft. long cheater bar. Start soaking the bolt's and nut's a couple of day's before you start the job.

[Mrwood]

If i pull my cover off my rear end, how can i tell what gear ratio i have in it. I have a friend who is going to put my 3.08 gears in for me. but i need to measure my ring gear so i can order the correct kit. He said there are 2 sizes of ring gears, 8.50 and 7.50 so when i get the cover off is there any way to find what gear ratio i now have. Thanks all who help me on this matter.

[sqzbox]

Usually, you can find the ratio stamped on the edge of the ring gear. You can also count the teeth on the ring gear and pinion gear and divide the ring gear # by the pinion #. (gotta love calculator's over pencil and paper!).

[Mrwood]

Originally Posted by sqzbox

A 5 speed would be a good choice with the gears you have now.
You have to consider that with the 5 speed you'll need a new floor shifter and relocate or change the cross member location. A few other things would be clutch linkage compatibility, back up lights, and I'm sure an issue with the tranny to drive shaft yoke.
It might be easier to just swap out a different rear axle with the ratio you want. 3:08's would still take off ok with lower hwy rpm's.

I'm with big gear head on this one. One tip is geat a can of PB Blaster and a 3ft. long cheater bar. Start soaking the bolt's and nut's a couple of day's before you start the job.

Well i got me a 5 speed for a good price, so now its tear down time. I think i will be happy with this choice. Thanks for all you that have helped on this matter.

[cobalt327]

If you're still unsure or curious, unless the gears have been swapped look on the inside glovebox for the RPO sticker:

Axle Ratio RPO Codes

GU4=3.08
GU5=3.23
GU6=3.42
GT4=3.73
GT5=4.10
HC4=4.56

G80 - limited slip