I just installed the 4203 on my 2010 M8 this past week, not a complicated job, but I found I can use a couple more tools in our garage! I first tried the 5203 as I was able to get it flush to the end of the shaft......no such luck on install as the cases would not close. Next I pulled that off an installed the 4203, fit like a dream.
I will say the bearing I took off my sled had only 600 miles on it, it rolled smooth and sounded pretty good. The OEM 6203 bearing on my sled was also sealed a little different. My stock bearing was made by PEER and had black seals not orange. MFG was in China. I believe that PEER is the bearing MFG used by BDX as well.
Overall:
I look forward to using the 4203, I think the double row bearing should be a nice improvement over the stock 6203. I also think the 7203 bearings on the market would be a very nice improvement as they are single row angular contact and would fit without any issues using the stock spacer on the shaft. Also I needed to replace the gasket on the case, thankfully my dealer had one in stock
I will note that I had one whole on the inner side of the case closest to the tunnel that I ate up some threads on. Not sure how it happened exactly but even after cleaning it up with a tap I could not get enough torque on it. I ended up drilling it out and putting in an insert which worked perfect. The insert I used was a 6mm x 1 x 1.5 for the Torx head screws. I actually wish CAT used some insets on these, although more expensive, it is always little risky fastening steel into an aluminum case For me Anyways
