i already know mine is LSD. i just was trying to figure out why it is. why would mazda put out that 91 coupes do not have LSD. when some do. i have only seen one good answer. that maybe there were left overs from 90 and put them out as 91's. i dunno....its kinda interesting to me but annoying at the same time. you never know what your gonna get type thing...

None of the 89-91 Mazda brochures show an LSD differential as either standard or an option on N/A models beyond the GTUs (Not GTU). 89-91 N/As did not come STOCK FROM THE FACTORY with a LSD differential. Beyond the brochures, the following information also indicates that there were no stock 89-91 4.10 LSD differnetials.





Mazdatrix: No mention of any 89-91 N/A LSD



http://www.mazdatrix.com/g8.htm



Mazda Motor Sports: There's good info, but again no mention of any 89-91 N/A LSD. Go to Page D8 and check the stock unit and you'll see it references "early models" or S4s. Go to Page D9 and you'll again not see any parts listed for an 89-91 N/A LSD. If fact, there is no mention of any STOCK 89-91 LSD.



http://www.mazdamotorsports.com/wcscp/pdf/...differential%22



If that's not enough, go the 86-88 Mazda parts Manual Section 2710 (Upper Left Hand Corner). There are three differentials listed N/A Open (Normal), N/A (LSD), and Turbo (LSD)



http://www.wankel.net/~krwright/files/manu...3%20CHASSIS.pdf



Now go to the '91 Mazda parts Manual Section 2710. There you will see only two differentials listed Open (Normal) and LSD. Look carefully and you'll see the Open lists the Coupe and Convertible, along with a different Part number for the Coupe Automatic Ring Gear. There is only one listing for an LSD differential and since all Turbos came with LSD, this is the listing for the Turbo differential. N/A and Turbo differentials are NOT a direct interchange.



http://www.wankel.net/~krwright/files/manu...4%20CHASSIS.pdf



Finally check the 89-90 Mazda parts Manual. Again Section 2710. There are listings for both N/A and Turbo LSD. But compare the part numbers for the ring gears between the normal (open) and the N/A LSD.



Open, which we know is a 4.10 is MO55-27-110A. The part number for the N/A LSD ring gear is MO66-27-110A, which is for the GTUS 4.30 ring gear. Again, no reference to a 4.10 LSD. Further, the MO55-27-110A part number is also the part number for 86-88 N/A 4.10 ring gear both Open and LSD.



http://www.wankel.net/~krwright/files/manu...5%20CHASSIS.pdf



Again, there was no STOCK FROM THE FACTORY 4.10 N/A LSD. If you have CORRECTLY identified an 89-91 differential as LSD, then it was changed out for an S4 or GTUs or an aftermarket.

im not gonna argue with you...but mine has not been changed out. also same story from other people. and i DO definitly have a LSD. i know the brochures and all that say they dont. thats one of the reasons i started this post.