If you buy new truck you pay fet, which you dont when you have used. Also your monthly insurance will be very high for the new truck.
After 3-4 year your new truck will start to break so you will do yoyr truck payments plys pay the repair bills.
I think best trucks are before 2003, so you dont have to deal with egr, dpf, scr ans sensors.
I have 2001 volvo paid for this truck 15k with fresh rebuilt engine, when spent another 16k to rebuild tranny and rear ends.If you can do small repairs yourself you will save alot.
So you can do the math what is better.
I have an 03 kw t600. At 1.2 million. Paid off for years. It's time for an overhaul. I was in your shoes but for the 30k overhaul I know I'm getting a new truck instead of 30k on a used truck that has more of a chance to brake down vs the rebuild. My thoughts