I know a guy with a Super Stock 318 Aspen that uses mid-high 5.xx ratios and it wouldn't surprise me if a 5.38 could be used in a Stock class 340 stick car in the 1/4. Heavier cars can sometimes use more ratio also.

Maybe enough people are getting away from the more expensive and less efficient Ford 9", making these Dana 60 ratios worthwhile to manufacture.

Comp cars and what use to be Modified production like all that ratio too with their itty bitty engines.