I don't think the carrier bearings changed I think its just the inner seal your worried about. Just my $0.02
They dont use inner seals on rear 60's , the hubs run in gear lube.
So changing the spindals to the late model 35 spline spindals?
Just cut yours off bore and replace
requires cutting them off and boreing to size and welding back on which also requires alignment jigs to keep it straight.
I did mine last year and it was quite easy, but then I also have access to mills and a lathe to build my jigs.
sounds like alot of work, maybe I'll just buy some quality 30 splined axles and call it a day?????
If your going to spend $$$$ for shafts get the 35 spline and dont look back, do it once and do it right, besides I dont belive any body makes HD 30 spline shafts.
Here is a pic of a spindle in the lathe