So, I'm in the process of piecing my 305 back together with some factory improvements (l98 cam, better headers/exhaust, 416 heads), and I'm looking for advice on a rear end.

From what I remember, it's a 3.27 standard (non-posi) rear end currently. Next tax season my project (if the 305 doesn't end up toasting before then) is to replace this with a posi rear with something like 3.7x gearing. The trouble is, I know almost nothing about rear ends.

I'm looking for advice. I will have around 1300 to play with, what are my options? What's cheap? what's good? What do i need to look out for and be aware of? Is it possible to swap the guts or should i get an entire assembly?

Any suggestions on reading material? A hint on what to bolt on would be fine, but I'd like to understand what I'm doing as well.

MY WANTS: Posi-trac. Has to be. I'm looking to keep the operation as simple as possible and use reliable components that I dont have to worry about. If 'the hard way' is substantially cheaper and still doable with standard garage tools and a bit of hard work, I have no problem doing it, but if the expensive route is bullet-proof and hard to goof up, I don't mind spending a few extra benji's.

Let me know! Thanks in advance,

J.

 

3.27 would be a 9-bolt. If so, check the following link for info that may prove useful:

https://www.thirdgen.org/forums/faq-...now-about.html

If you have 3.23's, you have a 10-bolt. More info follows:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

If you want something that will last for a long time don't replace what you have with a stock rear end. Everything from 82 to 92 is very weak. All third gens came with 26 or 28 spline axles. Your best bet is to save a bit more cash, for around 2grand you can get a rear that will last a very long time, and you won't have to worry about breaking it.

 

Goodness that is a lot of information to absorb! Anybody got a link to a diagram of a rear end so I can see what parts they are referring to (carrier, axle spline etc)? Been googlin' around a bit but no dice so far.

Is it safe to assume that swapping to a better rear wont be as simple as 'pull old rear, slap on new rear'?

 

Swapping rears is straightforward, one in, one out. However, if you go from drum to disc, say, you'll need a disc combination valve and parking brake cables. If the new rear's ratio, isn't the same as the original one, you'll need to change the drive and/or driven gears to make the speedo read correctly.

JamesC

 

Count the number of bolts in the cover. If it has 9 bolts with a rubber plug in the cover then it's a Borg Warner 9 bolt. If it has 10 bolt in the cover then it's a GM 7.5 10 bolt. This is the first thing that you must figure out. Come back and let us know what you find.

 

okay guys get ready to have a good laugh, but i am new to all of this stuff and really want to know exactly what you gain/loose by going from say, my stock 2.73 rear gears to say a 3.73? more accl.? more top end? What? Thanks for your patience.

 

2.73 will give you more top speed and lower engine RPMs at crusing speed. 3.73 will give you quicker accelleration, more tire smoke and higher engine RPMs at crusing speed.