Your stupid question was about 20..25..30 etc. dispensations.
Like I said, it is clear that there are at least TWO. So start from that.
So those that say that there is ONE gospel are just plain ignorant. There is just no other way to say it. The Bible word "GOSPEL" simply means GOOD NEWS (or GOOD MESSAGE). That is ALL. The Bible NEVER explicitly connects that word with just ONE thing. There are MANY "good news" in the Bible.
Like this one:
Gal 3:8 And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed.
Paul makes it totally and abundantly clear that THIS gospel was the GOOD NEWS that "In thee shall all nations be blessed"
That "blessing" is not specically about eternal life, though many will try to force it to say that.