I have a 2000 yukon and all I can say about it is that it has had 3 heater cores and could use another one. They keep getting a tiny pinhole leak in them and the entire dash and steering column come out at the dealers for replacement.
It has also had a problem with power steering pumps, and it could use another one of those as well.
Both the above were covered while my dad had it since he had an extended warranty. He has always been gm, bought lots of new stuff from the same gm dealer.
He won't even consider a new gm now, and a used one is worse after seeing what his has been through.
The vehicle is driveable and the problems are annoying but I don't care since I am going to trade it in on a diesel dodge or ford in a few months.
As far as guns vs. vehicles, you have to decide to some extent since you have no vehicle. With a vehicle comes upkeep, fuel, insurance, and headaches if something goes out on it. The reason you can afford guns right now is most likely because there is no vehicle sucking your wallet dry.
If you can get along without a vehicle I think it makes sense to wait a while before getting one.
That said, having a vehicle at my disposal allows me to go shooting or shopping or anything when I wish to do so.
The one nice thing about guns is you can shoot them and abuse them and they still sell for a higher percentage of their original price than a well cared for but well used truck.
Personally I would get the truck but I hate gm.
I was a mechanic for a bit and all vehicles have their problems. But gm has soured me with personal experience and I want a 4x4 with a solid axle up front so no gm here in a few months.