No. As a good rule of thumb, it's not smart to trade for a vehicle that has a lot more miles than what you're signing away. Especially that incredible difference. You're talking a 79,000 mile gap, no pun intended.
And for a 6-7 year old truck? Ehhh... Does it have a hemi? Reg cab? SLT? Laramie? Custom enhancements?
Furthermore, the dealer's... deal... sounds, smells, and looks fishy. If it's too good to be true, it is. The fine print probably says your sending your first-born into slavery. The average grizzley bear is friendlier than these snakes.
I can understand you want a Ram. They are so damm kickash. But not this one. It's too old, too used, and too suspicious.