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 !
 
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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.