need differential advice , please help

Get the 60" blade if you like. You'll have no problem. I wish mine was a 60".

Yamaha had issues with the rear diffs popping out on the 660. They released a superseded part number with a newer clip to fix the issue.

If guys were still having issues after that, in many cases replacing the axle cured the problem.

My Grizzly 660 had the RH axle popping out when I got it. First 3 rides had the axle pop every ride. I replaced the axle clip only with the superseded part number and it never happened again.

6 months ago I had to replace a complete axle on a 2005 Grizzly 660. The axle popped out on the owner and it chewed the splines off the axle. All that hard metal chunks just like you got now. Remove the seal to clean it all out. It will not go through the diff like you think it would.
I replaced the seal since it got destroyed when the axle popped out. Flushed the diff and a new axle and he was on his way again. I did a follow up inspection on his rear diff 2 months later to check for loose or worn bearings and everything was still tight and leak free.

Hey Dezz thanks so much for all that incite you seam to really know your stuff. You wouldn't happen to know the right part number for that clip would you? Can I buy it online? Ive specifically gone to my yamaha dealer four or more times over the years asking again and again about this new clip, every time they tell me it dosn't exist. Im only going to argue with them so much ( can't believe everything you read on line right?). Also im definitely going to replace the right axle and inspect the left one. Would you recommend buying an oem part especially if only replacing one side or an aftermarket? Im worried the oem would just have the same defect. An if after martket any brand suggestion? People on here seam to call the gorillia axles junk which is news to me. Again thanks for your time i really appreciate it.. And Reogem thanks for your suggestion as well, Ive never noticed the clips being different on the sides from memory but ill be sure to look close and keep that in mind. Ive been cleaning this out and reattaching it all at least fifteen times a year, and just pushing it back in many dozens more. Now I have two new babies and I just need it to work, there's no time for that anymore. Such a great reliable machine with this one thorn in my side

If it were mine, I would replace the entire axle and be done with it. Do not buy an OEM Yamaha axle. You'll probably choke on the price of it.

My favourite axles for the 660 is Parts Discounter Heavy Duty axles available on eBay. In my opinion they are the best bang for your buck axle. Way stronger than stock and priced right. I have all 4 in my Grizzly.
Gorilla axles are not junk. They are fantastic axles.....but they have a price that is beyond justification. They simply are too expensive. Where I live in Eastern Canada, one rear Gorilla Axle is about $500. I can get "all 4" Part Discounter axles for much less than that...and they ate the same size and material as Gorilla axles.

You can purchase Yamaha parts from dozens of websites online. Just Google Yamaha ATV parts.
The part number for the new clip is: 5KM-2536E-10-00

The reason why your dealer says there is no "new" clip is because of how the Yamaha parts diagrams are made. This new clip came out in 2006, and was already on the 2006 models. 2003-2005 models had the old clip. When you look up the clip for a 2003-2005 model, you'll find you can't get a part number for that clip. It's not listed. You have to go into the 2006 to 2008 model diagrams to get a part number.
Rather than update the old parts diagrams with the superseded part number (which they normally do), Yamaha simply deleted the clip information altogether. So since this information is simply deleted/not listed, your dealer probably just thinks there was no other/different part number.

close out

Hello out there and thank you for reading, just wanted to take a few minutes and close out this thread as well as give a little advice to anyone replacing the differential seals or rear axles with the newer clips. First off cheers to Dezz for all your help I cant thank you enough. The clip number from Dezz worked great, it took my dealer a month to get them in but it beat paying $17 shipping on a $4 dollar part online. I replaced both diff seals, and both rear axles with the ones you suggested. I finished about 1am and immediately took off tearin threw the woods. In the past it was at the point if the tires spun in mud or snow it would pop out right away as soon as the tires got loose. We had about five inches of snow and I rode a quick 5miles spinning the tires as much as I could, so many doughnuts that Iv'e longed for. So far the axles have stayed put after that hard ride with no leeks or signs of slippage. The metal shavings that I found in the diff this time and the last time i cleaned it all out were definitely from the axle spline just as you suggested. There was no visible damage to the diff itself. The rear left axle on the inner part of spline was stripped pretty clean and a cork screw like gouge was worn into the axle and the circlip was seized between the splines. The seal on that side was worn right through the rubber flange and had severe ware through out, Ill try and upload pictures after. The problem was slowly getting worse I can not believe how smooth it rolls now in neutral and how much more power and speed it has regained with out the resistance. The cv boots and the diff seam to get warm after the ride and I assume it is just normal or breaking in a little. Also my diff seams to be tilted ever so slightly to the right, is that normal or have i bent it a liitle through out the years? lastly a couple tips, the seals in the past were always a pain in the ass, this time i tore a small piece of the rubber off so I could grip the metal with large vise grips then turned it like a key,, the metal crumpled inward and popped out and it took all off twenty seconds. As for the new axles and clips I read a lot of people talking about needing to use a hammer to get the new clips to pop in and that just seams like a bad idea. On the lift i placed the quad up against the lolly column and was able to put slow even pressure and pop them right in. Lastly if anyone gets these axles there great but you'll use one of those bendy pins on the retaining nut for the hub, your plastic covers wont fit over them so just cut some vertical slices in the flange and they will spread out and fit over the pins and then the tire will keep it in place. Hope this helps someone and i'll be sure to follow up if any problems creep up. Thanks again Dezz

well that all sounds exciting,, thanks for the heads up. My welder is currently having feed troubles and comes out all jerky, for this reason and having no time with two babies I ended up ordering the bracket from turner cycles. It was 65 for the part and 24 to ship to Ct. (ouch). Also after my first hard test ride everything seamed great and then after taking my baby for a two mile slow and easy ride when I went to look at it last night there a small puddle of fluid. Not sure why, the axle is still in properly and I know the seals were set all the way in. Is it possible I over filled the fluid? I thought you were supposed to fill it from the top till it was full, seamed pretty easy. The fluid I used was yamalube friction modified shaft gear oil sae80w-90 api service gl-4,gl-5. It did seam thinner then the previous yamalube I used to buy. Any help is always appreciated ,, thanks again