Judah is NOT the literal second son
Judah the riddle second son
As the fourth son, God plays riddles to make him the second son. Levi was not to be numbered as one of the tribes.  And Simeon and Levi would be dispersed.  With two of the first three sons out of the way, Judah becomes the second son.
Judah plays the role of he second son as well. The promise and blessing goes through him to Christ.
Since man and his wife are one flesh: Judah and his Adullamite wife are the first flesh, and Judah and Tamar are the second flesh. His son’s from the Adullamite are not fruitful, 
A man and his wife are one flesh: Judah died with his first wife, yet continued to live. 
There is a dramatic change in his person with a scene of the cross in the midst. He is a man of the flesh as he deceived Jacob into thinking that Joseph is dead.  But then offers himself for his brother Benjamin’s life.  Between the two events, Judah had been placed in prison by Joseph, as a picture of the cross.
Judah exchanges sin with Tamar, as Christ exchanges our sin for his righteousness, and she is proclaimed to be more righteous than he. 
- ‘יהודה – God יהוה with a declaration ד in him ‘ or ‘praised’
- ‘see ראו a son בן’
- ‘hear שמ depravity עון’
- ‘teach ל creation (God’s purposes) י with clarity’
- Nu 2:33 But the Levites were not numbered among the children of Israel; as the LORD commanded Moses.
- Ge 49:5 ¶ Simeon and Levi [are] brethren; instruments of cruelty [are in] their habitations. Ge 49:6 O my soul, come not thou into their secret; unto their assembly, mine honour, be not thou united: for in their anger they slew a man, and in their selfwill they digged down a wall. Ge 49:7 Cursed [be] their anger, for [it was] fierce; and their wrath, for it was cruel: I will divide them in Jacob, and scatter them in Israel.
- Ge 38:7 And Er, Judah’s firstborn, was wicked in the sight of the LORD; and the LORD slew him. Ge 38:9 And Onan knew that the seed should not be his; and it came to pass, when he went in unto his brother’s wife, that he spilled [it] on the ground, lest that he should give seed to his brother. but those of Tamar are, and also get the inheritance.
- Ge 38:12 ¶ And in process of time the daughter of Shuah Judah’s wife died; and Judah was comforted, and went up unto his sheepshearers to Timnath, he and his friend Hirah the Adullamite.
- Ge 37:32 And they sent the coat of [many] colours, and they brought [it] to their father; and said, This have we found: know now whether it [be] thy son’s coat or no.
- Ge 44:33 Now therefore, I pray thee, let thy servant abide instead of the lad a bondman to my lord; and let the lad go up with his brethren.
- Ge 38:24 ¶ And it came to pass about three months after, that it was told Judah, saying, Tamar thy daughter in law hath played the harlot; and also, behold, she [is] with child by whoredom. And Judah said, Bring her forth, and let her be burnt. Ge 38:25 When she [was] brought forth, she sent to her father in law, saying, By the man, whose these [are, am] I with child: and she said, Discern, I pray thee, whose [are] these, the signet, and bracelets, and staff. Ge 38:26 And Judah acknowledged [them], and said, She hath been more righteous than I; because that I gave her not to Shelah my son. And he knew her again no more.