My current DD toy is a '91 RS 3.1l, with the stock 3.23 rear. At my option, I have an '87 SC with the 3.42 rear in my driveway.

Was considering swapping the rears for the lower gear, hoping to gain a little more seat-of-the-pants torque. I've read that the older diffs have less splines, and therefore weaker axles. Is the risk worth the reward?

 

Not a lot of difference in your 323s vs 342s and yes the 28 spline axles are better so I would definitely leave it alone. Not worth the time. 323s are a really good gear in these cars due to the low rpm powerband they have. Im thinking of changing from 373 to 323 myself.

 

Good to know, thanks dmccain!

 

You won't break an axle with the v6; 26 spline vs 28 spline won't really matter. If you're bored, give it a try, if you don't like it, switch them back.

 

yes you want the 3:42 in there, forget spline count, meaning less at this point.

if you went high power V8 or big turbo 6, you wouldn't want either. swap it, thanks us later.

 

the only reason to have the 28 spline axles is cause then u could use the torsen unit out of the 4th gens , years ago when the 4thgens came out there was alot of these units out there for sale for 80-100 bucks

put the 3:42's in it u will enjoy it

 

26 vs 28 spline axles won't mean anything to you. It's a DD v6 car, you are far from the power needed to break 26 spline axles. Remember GM used the 7.5" 26 spline axle rears under 4, 6, and 8 cyl cars/trucks for 15 years (probably longer).

And truthfully even the 26 spline axles are not the weak point in these rears. It's the ring and pinion gears.

The smaller pre 1986 7.5" gear is weaker than the '86 and up 7.625" but both are still weak, and from my experience the R&P will break before the axles... At least they did in my 2 rear ends.

I vote for the 3.42 rear swap. It only takes a couple of hours to swap out a rear end.

 

Do I need to change any of the speedometer drive//driven gears to keep my speedo accurate, or will the difference be marginal?

 

To keep things right on yes. Also the ecm works better with the most accurate info it can get. Try it. If the speedo being off bothers you or it doesn't run quite as well then get the gears.

 

From 3.23-3.42 everything will be marginal including performance #1. Why bother. You will hardly notice any difference at all it just isn't worth it

 

I seem to have conflicting information here guys....

Will I, Or will I not have more Seat-of-The-Pants performance with the 3.42s?

I'm ready to do the swap now, But I hesitate to go through with it without a noticeable gain.

 

u will notice a lil bit , its a swap worth doing sinc eu have everything u need

 

you want big seat of the pants feel, drive way shift kit and higher stall TC...

 

Have any known good part numbers?

 

no, only done it to my Buick, but it made it a whole new ride.

firm shift kit, 2200 stall TC, went with RP full syn racing fluid for even more bite on shifts...

now rear end gears also make big changes, id still change to 3:42s but you can effectivly do that with a tire change, Buick again, put the 225-60-15 off the Bird onto it, it got off the line like a rabbit but pooped out over 80, stock 225-75-15 not as quick off the line but punch it at 80 and has life in it. [ Buick still has 2:73 12bolt rear end ]

 

 

Get a converter out of or for around a 98-2000 S10 and it will give you around 2200 stall, then a shift kit and you talkn bout seat of pants... I know because that's what I got. Along with 3.73 gears and a posi. I would have been happier with 3.23 or 3.42 though.

 

Would it matter if the s10 had the V6 or 4cyl?

 

no need for junkyard converters just goto autozone and buy the 105$ high stall , its the s10 converter and its new.

by the time u goto the junkyard and drop a trans for a used converter that could possibly be infront of a burnt trans u r just better off buying a new reman one

not to mention if u pull a converter fromt he junkyard and it has crude in it from the trans it will destroy ur transmission as well

 

Amazon or Autozone yea $125 unless you are short on coin yea don't get a "junkyard" converter... I wouldn't do that

 

I would never get a junkyard part like that, I just wasn't sure if the 4cyl trans and converter were the same as the 4.3l trans and converter, and whether or not either converter would mate to my 700R4.

 

I have a stock drum brake rear. And I have a 4th gen rear out of a 99 with the large ls1 rear brakes. None posi . It came out of a v6 car and o think they share the same gear ratio... Any idea what the ratios are?