The correct replacement hardware kit for your Fastway e2 4.5k system is the Replacement Hardware Kit for Fastway e2 Weight Distribution Head # FA92-02-9600.
The Replacement Bolts for Equal-i-zer Weight Distribution Head # EQ90-02-9400 you asked about is for Equal-i-zer Weight Distribution Systems.
There is not a specific lifespan for a weight distribution system. If maintained and the system is properly rated for your towing setup, it can potentially last for a long time. Over time, the... view full answer...
According to the folks at MaxxAir, for your 4761KS MaxxFan, you'd use # MA10A40009K for the smoke-colored lid or # MA10A40002K for the white replacement lid.
If you're wanting to let more light into the interior of your RV, I'd go with the white color, otherwise use the smoke-colored lid. view full answer...