Fit *perfectly*? Doubtful. This goes over the ring terminal for the battery wire connection?
Was the old one permanently built on and disintegrated so you'd have to cut the wire and put a new ring terminal on after slipping into same design boot? If it's so poorly made that it feel apart in only 4 years, I'm not sure that I'd want the same boot again.
If it's made like that, you could probably get away with a little oversized alternator stud cup size on it but the diameter for the wire would need to be right to fit the wire and hold in place snugly, unless you first slipped a piece of heatshink tubing onto the wire before put through the boot then heated that against the boot to hold it in place, but then you might have to cut that heatsink tubing away to take the boot off next time, or just put a wire tie (or small hose clamp) on the wire, or boot itself, to hold the boot in place.
Depends on the dimensional tolerances, think I'd start by using a caliper to get the needed dimensions and the wire gauge.
Lots of vehicles don't have that boot on the alternator, though it would be better to have than not, if there's a risk of shorting it while working on the vehicle or corrosion, though the latter can be slowed down with a coating of silicone paste grease or whatever else that is viscous enough to stay in place at operating temperature.
