48 pitch pinions?

Ok actually thats not that bad of an idea but i need to find a spur that will fit my buggy. right now it is a 88 tooth spur with a inner diameter of aprox 4 mm so i need to find something that will fit that. Got any ideas on where i should look?, i was thinking tower since they have a good selection of spurs but most dont tell the inside diameter, so im going to need your guy's help on this.