To add to what has already been said, you will be well ahead to get a knowledgeable person to look at what you have. Without pictures and more details it is difficult to appraise or assess what you have. Did your dad purchase this truck complete or has he accumulated parts to make a truck? Is the truck apart and in pieces now or is it whole? How much rust? Does it have a title? Is there an engine and transmission in the truck? Is it a three window or five window?

If it is in parts, it will be difficult to recoup the money spent and may be worth more if the parts were sold separately. A complete un-restored 1951 non-running 3100 pick-up sells on ebay and craigslist between $700 -$3500. A disassembled truck that needs repairs will sell on the low end. Add the parts and expect another $500 - $1500 if there is a buyer who would be willing to take on such a project or would be purchasing it for parting it out for the individual parts.

If the engine has no paperwork and is not running, it's to worth not much more than what a complete engine would sell for on craigslist or ebay $100 - $500. I will send you some links that may help you see comparable trucks for sale and some that have been recently sold. Good luck!