OK, so the 4.90 diff gears come from what years monteros montero sports??? eventually, I need to upgrade my 97 SR from 4.272 gears to 4.90 gears. Do you think going from 4.272 gears to 4.6 gears is a waste or will it make a marked improvement? I plan to put 4.6 gears in my LS for towing and 4.90 gears in my SR for wheeling. Both have 4.272 gears now. Opinions?

I'd certainly skip on swapping 4.636. Biggest cost would be in labor. You can find matching 4.9 in all 3.5L MSports and Gen 3 XLS 01-02

Well, I found a guy local that would do it $150 per axle. Think that is a good price? That is all this guy specializes in is diffs and drive trains, so it should be good work and its not far from where I live. I got the rear 4.6 gears from a friend for cheap and the front 4.6 gears got from M&S. So I thought I would put them in the LS for towing. It should make a significant change. From 4.2 to 4.6 that is .4 change, and I can do it all with parts, shipping and labor for about $650.00 Is that price worth the change (not that I can change it now, I have already bought them)

Like I said above. I'd go for 4.9. 4.6 won't make that much difference.But if you have the parts <img src="/forums/images/graemlins/scared.gif" alt="" /> You can find 4.9 fairly cheap. Like $150-200 per axle. The fron prob be direct swap. No need to set up gears. As to rear one. If you get 3rd member out of sport I beleive it would be direct swap as well. Added bonus would be a Hybrid LSD all 3.5l MSport Limited came with, or you might get lucky and get rear locker. $150 is cheap for labor though. I assume this is only for setting up gears you'd have to disassemble yourself.

No he told me he would do all the work, I bring him the Montero and the extra third member. I thought it was a good deal as well. It must be so easy for him since that is all he does for a living that he doesn't think of it as a big job.

So you say the 3rd member from a Montero sport has locker and lsd hybrid? I will keep an eye out for that <img src="/forums/images/graemlins/kewl.gif" alt="" />

BTW, just so I know, does the Gen II T case use the same oil as the transmission??? Just thinking ahead for when I need to get my t case gears put in. If this guy that I am having do my diffs also does T case gears and he does a good job on the diffs, I will have him do the T case as well.

I don't exactly remember which year was it. I think 99 then 00+ had hybrid LSD <img src="/forums/images/graemlins/kewl.gif" alt="" /> I believe it should be direct swap. But I stress the believe part I never 100% pursued this road since I don't have a need for one.

As far as oil t-case it uses GL4+ axle oil. It's been a long debate whether one can put GL5 in there. Personally I've been running Mobil 1 Synthetic GL5 fluid in there for last 6 years practically since I owned the 92. No issues so far what so ever.

alex is that the lsd/locker or just the torsen both scotts montero's have rear lockers in them. I think he will notice the differance only reason i say this is because after wheeling with guys that have the 4.27's that seem to over heat all the time vers the guys with 4.63's that don't have a problem at all(not working the engine as hard)

This is just an LSD albeit a good on. I didn't know his ls had locker alreadyThis is just an LSD albeit a good one except that 99 which had same locker as Gen 2. I didn't know his LS had locker already. 4.6 be of help for sure but still going into swap I'd go for best available option. That's just my opinion. Otherwise there is no sense to upgrade later to 4.9. Just money wasted.

Right, I see your point, but I wouldn't upgrade the LS to 4.90's later on, it would keep the 4.6 gears. It will never have a tire bigger than a 32. The 4.90 gears will go in my SR along with T case gears. My 'LSR' (although it can wheel some pretty serious stuff) will be primarily a camping/towing/everyday traveling 4x4 while the SR will eventually become a serious wheeling machine mainly used for sick off roading only <img src="/forums/images/graemlins/mrt.gif" alt="" /> or going on week long expeditions in the desert.

2001+ US spec Montero Sports with the 3.0L and disc brakes came with 4.90 gears stock.