This references the rear differential.
The Dana 36 was the smaller unit. It was used on all 1984 Corvettes, and all automatic Corvettes thru 1996. They were available in both 2-series and 3-series carriers, depending on the ratio, and have a 7.725" ring gear.
The Dana 44 was the bigger, and much stronger unit, used on all manual cars, 1985-1996.