Replacement Fuel Tank

I'm looking to purchase a 1987 Dodge Ram 50 with 100k miles on it. After taking it to my trusted mechanic, he said it needs a new gas tank and it is unlikely to find one so the reconditioning cost is $400+. I would like to eliminate that cost or at least reduce it. Does anyone know if the "Ram 50 Pickup 15 Gallons Dodge D50 Mitsubishi Mighty Max" will fit in the 1987 Ram 50? I can buy that tank for $80 on ebay, but it does not say it is compatible with the 1987 pickup line. Is there a reason why, and can it be worked around? Thanks in advance.

Its going to need to be from a 87-89 since those are the years of carbed engines in the second gen platform. And it also has to be the same body configuration, ie if its a single cab gotta be from another single cab and same with the length of the bed.