a newbie ,can buy 1979 Robinhood Dodge?

Welcome to RVing and the forum. My responses to you are based on your self-referral as a "newbie". If you haven't done it yet, take time to review many of the "new to RVing" posts on this forum. There is a fair amount to learn about RVs that will help you make a purchasing decision. You might want to consider hiring an experienced RV Tech. to evaluate the RV you are considering to help determine its strengths and weaknesses. Keep in mind that the most deadly RV "killer" are water leaks, especially if mold develops. The rig should be thoroughly checked for leaks. Request to see all maintenance papers on the truck part and generator. All tires that are over 6 years old should be replaced no matter how good the tread looks. For most RVs, age wears out the tires faster than mileage. Try to determine the Occupant and Cargo Carrying Capacity of the rig. This is the max weight of all people and stuff the RV chassis can carry. Especially with a young family, you don't want to place them in a dangerous situation by driving overloaded. Lastly, forget the seller's math, i.e., how much he put in it and such. All that matters is what the RV is really worth. Let the RV Tech help you with that. Best wishes for success.

Bob