I did another 3/16" AmSteel install yesterday, this time on my 96 Polaris XCR 600 SP.
It was difficult to get it through the hole in the spool reel, but I got it through.
I was not able to get it through the bushing in the housing or the recoil handle (not the OEM one for this sled) and I had to drill them out slightly to get the rope through.
This sled pulls MUCH easier than my 800 and I suspect OEM may use a smaller diameter rope. This may eplain why I was able to get it through on the 800 Twin, but not on the 600 Triple.
I suspect that 4mm AmSteel would have probably have gone through the holes OK and still be pleanty strong for this (or probably any) sled.
I found one place that sells the 4mm (5/32") Amsteel and it is rated at 4000 LB tensile strength (vs 5400 for 3/16") Not sure of stock rope tensile strength, but I suspect it is WAY less than 4000.