Advice on truck to mount crane on

First time poster here! I own a tree service and I'm looking to upgrade my crane soon. The plan is to buy a used truck and have a new knuckle boom crane rear mounted on it. the truck with crane will weigh about 50,000 lbs empty. It will not be driven very many miles (less than 10,000 a year) although it will be used 3 to 5 days a week for work, and spend the majority of its time at high idle running the crane.
I would like to spend less than $30,000 and I'm not necessarily looking for anything fancy. My top priorities are reliability, parts availability for the next decade or more, and not too expensive of parts. I am okay with something older as long as Parts availability will not be a problem.
It seems to me that certain engines or brands of trucks are known for being more expensive to maintain, or maybe more well-built and holding up better. I'm trying to get some input as to things to look for, or avoid. Thanks!

 

Thanks for the reply! However, I apologize for not being more specific. I will need a truck with tandem Rears and a tag axle as well. The weight of the truck with crane is around 50,000 pounds empty. (I just edited the original post to include that)

 

I think the crane weighs around 15,000 pounds and that does not include axillary Outriggers or the bed, or the subframe, or tool boxes, or ballast (so that it doesn't tip over). 50,000 lb is the number I got from the crane dealer for total truck weight. I have a crane currently mounted on a sterling 95?? series. It is a smaller crane than the one I'm looking to get, and my truck weighs 40000 lb empty.