Go back and read through the posts. This was very clearly answered.
do not get me wrong olderhermit, I do believed that Benjamin was born before Joseph was sold into slavery,
but I do not think it was clearly answered.
first the age of Jacob when he fled Esau was based on the assumption that Joseph storehouse was built for only a year...(containing supply for 7 years of famine) What if it took Joseph 2 years or more. (first assumption)
2nd In one of your post you reckoned that Joseph and Zebulon were about the same age, then in another you quote another one that shows Dinah had to be born first. (two possibilities)
3rd we do not know how long they have stayed in Shalem? (duration more likely to be an assumption)
4th the argument that 37 is a continuation of 35 without considering 36 a continuation of 37:
Gen 36:31 And these are the kings that reigned in the land of Edom, before there reigned any king over the children of Israel.
Also, Chapter 37 reckon that Jacob dwell in the land...of Canaan... which he did beginning in Shalem. (what if Joseph was sold while they were in Shalem) just an assumption.
all I am trying to say is; it would be better if we have a Solid evidence to support this belief..