2001 vs 2003 IRS

I did a search but couldn't find the answer I was looking for. I've got a '89 GT that I want to transplant an IRS into. I've seen several '03 IRS's on Ebay, but I thought they were a little over priced, so I put it off. Now I've found an '01 IRS that seems to be at a good price (with about 75,000 miles). My question is this, is the '03 IRS far superior to the '01 to deserve the almost $1,000 more price ? I know they both are 31 spline and the '03 half-shafts are improved in some way (?) and they come with 3:55's. Can someone tell me what exactly is different beside those things ? I will probably get rid of all the rubber bushings, add the differental cover brace and swap the 3:27's for 3:73's if I get the '01 IRS. Any info would be great !
 
I wouldn't say a used '03 IRS is worth $1000 more than an '01 IRS...the halfshafts in the '03 are somewhat beefier; that's the biggest difference I'm aware of. It seems you're already aware of the main differences (gearing, etc).
 
Thanks for the answers. I'm trying to educate myself on the matter and make a good choice. Seems like I read somewhere that the '03 and up have an additional brace called a launch brace or launch arm, or something like that, but I've not been able to document it for sure. If I bought an '01 I would definately beef it up as much as I could, but if I buy an '03 I will probably not poor anymore money into it. The '01 I was looking at on Ebay went for $886, I bowed out at a little over $700. Thanks again guys !
 
Look in SVT Forums Classifieds under suspension. I recall seeing 01 Cobra IRS's selling there. No way were they going for almost $900.

I would say $500-700 is about what I recall? This is usually without shipping so unsure how much that would add?


f/s- 03/04 cobra irs - SVTPerformance

Local p/u only but here is and example guy wants 800 for 03/04 IRS.

03 Cobra IRS rearend & Borla stinger IRS catback For Sale in NC - SVTPerformance

This guy would like local only pick-up but again a ballpark price number for you
 
You're right, the main differences are the halfshafts, the factory gears, and the differential brace. The brace is just a bolt-on piece that you can buy separately for around $150. The bushing replacement is very time consuming, I had about 25-30 hours in replacing just the lower control arm bushings and the IRS subframe bushings with urethane, but the results are great. I could never get the tires to chirp with the stock bushings, but with the urethane bushings it hooks up and corners much better.