gear ratios and torque
Stall is NOT a static number. A company can claim a TC stalls at 2500. Put that same converter behind a 400" 4" arm (500#/ft)and a 273" (325#/ft) stock stroke engine. Is the converter going to stall the same? Nope... 273 will stall lower.
Same with changing rear gear. 3.23's put more load, same as the 4" arm engine, on the TC.