good rear end?
 

i am looking for a good rear end for my 69'. I want more speen than tork, i am puting a 350 4 bolt main in it. Any sugestions? thanks for the help. :)

i am going to put a 5 speed manuel transmission in it btw.

GM 12 bolt will handle that small block all day long, they are cheap and easy to get.

best place to get one?
and whats the difference between a 12 bolt and a 10 bolt?

I look on Craigslist, salvage yards....any 68-72 Chevelle 12 bolt will bolt right in...there could be others and maybe someone will chime in on them.

What is in there now?

If its not a 12 bolt, the 10 bolt that is in there should hold up unless you put some real sticky tires on it and are doing 5 grand hole shots.

A 12 bolt is a stronger rear end than a 10 bolt. SS (big block) cars came with a 12 bolt. Like Ric said a 10 bolt should hold up well behind a 350.

Why do you want to replace the rear that's in there, something wrong with it?

well right now i dont actually know, i am doing a rebuild and its a old looking rear end, i was going to be replaceing it becuase i did not know what it is, and i am puttting an manuel tranny in it where it had a automatic.

If there is nothing wrong with the rear end that you know of, I would just clean it up and let it be. Rear ends usually don't break unless too much power via 5 grand hole shots or netural slams. In all my years I have to say I've blown a rear end.

Not sure what to tell you. Is it a posi rear? If not then you might as well upgrade to a 12 bolt. On the other hand you said you want speed not torque, most likely the 10 bolt that is probably there now will have a gear ratio that will give you that.

If you find a used 12 bolt on craigslist it may not have the gear ratio you want and may also need a rebuild.

Count the the number of bolts in the rear cover, either 10 or 12 bolt. Lift rear wheels and try to spin one wheel, if one turns and the other turns in the opposite direction, trans in park, then it's an open or non-posi rear. If it's a posi rear you won't be able turn either wheel.

If it's an open rear then block one wheel and put the trans in neutral. Turn the other wheel one full turn and count the number of times the driveshaft turns. That will tell you what gear ratio you have. Could be anywhere from less than 3 to over 4, which I doubt. Be as accurate as you can while counting the driveshaft rotations.

If it's a posi rear end then leave both wheels in the air and put the trans in neutral. Then do the same, spin one tire one full turn, the other should also spin one full turn, and count the driveshaft rotations.

Driveshaft rotations won't be an even number of turns, could be 3.42, 3.73, etc.

What rear end gears should i just for good highway and street use?
i have on my 70 gto th400 transmission and a 383 stroker with a mild cam i dont know the cam specs i forgot. and my rear end a 10bolt and my tires on the rear are 275/60/15s what good rear end gears would be good for highway and street use and i dont race it i just want that extra punch for the street and good highway performance aswell something in the middle of both highway and street

I would stay in the mid range 355, with the size tires you have. SS cars came with 331, but are not available unless you find a used set.

My opinion 3:73's are a good set of street gears. Stock tires are usually about 24-25" in height depending on the tire manufacturer. You can look at several tire manufacturers tires in the same size range, then look at the actual spec sheet. They can vary in height from 1-2". Its crazy but true.

With the 275 tire you are probably somewhere in the 27" tall range. Going from a 25" to 27" tire, your final drive gear ration is reduced anytime you go up in tire height. So if your stockers came in at 24 and your now at 27, thats a 3" difference and that will make a big diff on final drive ratio.

Im running a 295x50x15 on an 8.5 Weld drag lite on my 84 SS Monte Carlo with a mild 350, turbo 350 trans ( No overdrive ) and a 3:73 rear. At 60-65 Mph im at about 3000 rpm. With an overdrive tranny, that would drop down to about 2200 maybe less.

In my Suburban on steroids with a 35" Tall Tire with 3:73's and a 4l80e overdrive tranny at 60mph im running less about 1800rpm as a comparison.

I would go 3:73's if your running a auto tranny with overdrive. Its a fun gear and the car will like it. My SS Monte is fun to drive with the built tranny and rear gears ( not as much fun as the Chevelle though ).

In the Chevelle Im running 4:11's with a 33" tall tire, that cuts the 4:11's down to about a 3:73 or so.

Word of advice, if you do change the rear gearing, let a professional do it, otherwise your asking for trbl, IMHO.