Wondering if this boat was made in 1990.or is it a 251.Im told it is a 253.But I did not think they started making it until mid 90s.

That boat should be a 251, I think you are right the 253 came in the Mid 90's.

Measure the beam the 253 had an 8'6" beam and the 251 has the 7' 9" beam. The boat is night and day differenece in handling rough water and the 251 is much faster.