the d150 tank is totally different than the '89 Ramcharger. The RC tank sits in the very rear of the truck between the frame rails. The D150 tank sits on the side of the bed on the outside of the frame rail.

BTW - solved the problem. Turns out it was a small crack. Was able to "plastic weld" it and now she's as good as new. While I was at it, I replaced the in-tank fuel pump and strainer. Glad I did that