Is an 8 1/4", 2.45:1 diff housing exclusive?

My BOG friend had a 170 with a (unknown to us at time) 2.45 rear out of a Cordoba. That car couldn't climb a steep driveway! We gave him a 225 and then we found out the rear was an ultra short 360 sled rearend. never liked 2.76 gears try to find some 2.93s or one step better, 3.0x?
Carrier break: Chrysler 7.25" 2.47 & Down 2.76 & Up...ouch!