I want a 3.73 geared rear for my car, but in summit's catalogue it seems the best bet is an Eaton posi which is like $450. Is there something cheaper? It'd be nice to get rid of my one-legged burnout problem, but it'd be nice to do it for less $$$ too. You guys are probably more expert than me on the topic, and this is only my daily driver streeter so I don't need anything fancy...

 

If you have a 10 bolt, check out www.slponline.com, and look at their torsen take off posi units. That's about the best deal going, $80-100.

[This message has been edited by ebmiller88 (edited December 05, 2001).]

 

ssshhh! don't make such a big deal about the SLP posi's, there may not be many more of them available after they stop doing the conversoins in 2002. Just kidding. I got mine when it was on sale for $75, and I think that every peg leg deserves one. -Randy

 

Whoa, Chris, I just saw that you have an 87 car. You most likely have 26 spline axles which won't work with the slp unit. You might find yourself spending over $400 to get a posi afterall. - Randy

 

87 T/A likely has a 9-bolt, which won't accommodate the SLP unit anyway.

The first thing you need to do is determine which rear end you've got. Look at the cover and count the bolts, there will be either 9 or 10; if you have the 9-bolt it already has posi. If you have the 10-bolt you probably don't have posi but the SLP unit will work, except that you'd have to get some 28 spline axles from somewhere and those are about $250 a set.

If you have a 5-speed you probably can put a 3.73 gear on your existing carrier, because it is a 3.23. If you have an auto trans however, you probably have a 2.73 or 3.08 if it's a 10-bolt, or a 2.77 if it's a 9-bolt; yo have to use special gears (thicker) to put a higher ratio on that carrier, and I doubt such gears are avilable for a 9-bolt.

All in all, before you start buying parts, you need to be absoltuely certain of what you've got. Pop the cover off and look, it's the only way to be sure. You need to know which rear it is (9- or 10-bolt), and what gears are in it now, to be able to get the right thing the first time.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

Sorry, it's been a while, been busy with finals. I appreciate all your help guys. I almost choked when I saw that I could get something under a $100. I have a 10-bolt by the way and I calculated 3.08 rear gear ratios with a .7 OD on my 700-R4. So what, do I have the lame 26 splines? What are my options now? $400 and up, eh...?

 

It's a safe bet you have 26 spline axles. The only chance you have is if the previous owner was also a "modder" and already got a new diff for some reason. The slp units are nice, but you need 28 spline axles. You also need series III gears, which you have already said you were going to get. What other kinds of mods do you have on your car? If all you have is a near-stock 350 making less then 275hp, then I think your 26 spline axles are strong enough for you, and you should buy an aubern posi unit from summit. They are stronger then the $100 slp units, and you can get them for your 26 spline axles. That way you don't fill up your garage with old parts. -Randy

 

I can't find the Auburn posis on Summit's website. How much are they? Do they come with the gears? By the way, yes, it is a stock 350 with headers soon to come, but pretty mild (I doubt I'm even near 275hp-- probably more like 220 if that) but I'm planning on getting a nitrous kit down the road after I fortify the chasis, so are 26 splines enough? I don't want to have to tow my car home when I finally take it to the track.