The differential HOUSING was originally engineered for 1990 Mustang. The housing is for an 8.8 it and was used until a major revision was required.
Date on the tag is from 1995.
S207C = axle code (S = Sterling axle plant)
X
3L08 = 3.08:1 axle ratio, Traction-Lok differential
88 = 8.8" ring gear
5C29 = axle assembly built on March 29, 1995