just saw this post where you were asking about 4.90s. Here is the info I can provide on the upgrade:

yes and no, some sports had them, some didn't........I did a lot of research on this when my brother was looking for them.

Yes, I have 4.90s in my SR, I bought them brand new, part numbers are:

MR124860 Gear Kit+fr Diff

MR124858 Gear Kit+rr Diff

I think with shipping they are like $900 or so, but there is a better way but requires more leg work:

when my brother put on 35s on his 99 montero, he also wanted 4.90 gears in both diffs. I saved him some money by locating the third member and the front diff for only $500 out of a montero sport. Here is the catch:

1. you need to locate a 2001-2004 montero sport with the 3.5L engine that can donate both front and rear diffs

2. ask them to verify that it does have 4.90 gear ratio in both axles

3. have the part yard give you the VIN from the doner truck

4. take VIN to a reliable parts dealer and ask them for the part number for the front and rear ring and pinion gear kits for that specific VIN

5. If the part number they give you matches the part numbers I gave you above, work a deal with them. I got the rear third member and front diff shipped to me for $500 which was $400 cheaper than buying the gears brand new.

6. I haven't cracked open the diffs to see if the gears will actually work yet, but according to VIN and several part number checks with different sources, they are the same exact part and should work.

also, these 4.90 gears were also fitted in some of the early gen III monteros, I just haven't nailed down exactly which ones yet.

using the VIN and cross checking the part number should do it though. I think 2001-2002 full size gen III monteros had them too, but use the VIN to verify part numbers.


HTH and if you have any other questions, let me know.