You seem like you would have a good fico score, I would imagine you could get around 3% money.
That new truck is going to go up 5-6% each year you waste saving.
So basically you are losing money trying to save up for this purchase.
(providing that the payments do not put you in a bind)
Trucks are not going up 5% a year. But yes, with interest rates so low unless you just don't like big payments I'd finance 100% of the truck and use any savings to assist with making the payments if needed.
No reason you can't see 2.58% @ 60 months, 2.89% @ 72, 3.39% at 84.
I'd generally avoid an 84 month loan. I'd also buy GAP insurance if you do that.