The underdash units are pricey, but take these things into consideration.

1. installing factory A/C into a non A/C truck..... A LOT OF TIME, plus you have to get a donor truck. Could end up being a HUGE project. Also, unless given to you, you need to spend some money on a donor truck.

2. Having a dealer install A/C into your truck. Probably going to be more expensive. Unless you work at the dealer and can get the parts for nothing.

3. If you want A/C and want a more easy job of doing it....buy the underdash A/C unit.

Really, It can come down to time. Do you really want to tear your current trucks interior down along with a donor truck's interior? Plus, cut that big hole in your non-A/C cab? But, sometimes the bigger jobs are more fun. Who wants to take the easy way out?