I'm in about to purchase a 1992 D250 single cab. Truck is all original but needs some attention on the roof. Did some research on fixing it, just not sure what's the best approach. The rest of the cab and truck is in great condition. I was reading that all the cabs in late 70's to early 90's are the same. Is this true? I'm sure some of you have done this before. Any input would be great.