From the doors back - nothing is a good swap from any of the repop pickup patch panels.

Metal Man (Ray Stanley) made a new rocker for me that worked very well (between passenger door and front of wheel well).

He can make about any part you could need including fender patch panels and rear corner patch panels.

Do a search for Metalman and see if you can come up with his e-mail address. His parts are top quality and will save you hours of extra work trying to make other parts fit that were not intended for a panel/suburban.