should I buy it, and will it worky?
 

I can get a steel on a 93 dually 4x4 6.5 turbo diesel, already has second tank for converting to veggie.

The seller states that it started very well in California, but the last two months in Washington's cold has been harder and harder to start, and now won't start at all, I tried to turn it over, to no avail. Could it just need new glow plugs?

I recommend actually getting a High cold cranking amp battery for it particularly in Washington. I live in WA and I spent the extra money and got two powerful batteries(my truck runs two batteries wired in parallel. I am running approx 1700 cold cranking amps and approx 2000 cranking amps. to start my rig. Starts right up every time after the plugs warm up. I had a similar problem this winter, turns out batteries were the solution. Worth spending the extra dough on the interstate megatron plus. Great cranking. New plugs can also significantly reduce starting time. I try to clean my plugs once a year or so with kerosene to get some of the deposits off and can aid in starting. I dont know how long your plugs have been in your rig, plugs might need replacin.

or the veggie clogged the IP..

have ya tested them?

Pull an injector and see how coked it is.

Check other threads here and do some reading.

Check for fuel at the T/drain, check/change the fuel filter, Jumper the lift pump and run fuel out the drain. Etc.

How much money for the truck?

What condition?

Load test batteries, clean battery cables, clean grounds, make sure your fuel has not gelled.

That's off the top of my head.

And all of that is no cost items to go through first before you start throwing parts at it....

Yeah, without a meter, you're kind of guessing. I've routinely been wrong the first 4 times guessing. Some test equipment is a great investment.