Different Gear?

I'll say it's 2.7 something or the other, 1-3/8x2 or 1.375x2=2.75, but online gear calculator showing 2.45 with a 26-1/2 inch tire and 2100 rpm. I may have to concur with 2.45, as I am 2250 at 60 Miles per hour with 25-1/2 inch tire with a 2.76 gear. I however, hope it is not 2.45, as I hate when someone has to change a whole axle to gain a better option for ring and pinion choices. I cannot find the thread on 8-1/4s, but I believe the high ratio housings had a different casting number. Best check that first.