I assume you mean GCWR?
OK, 8800 plus 250 for hitch means your truck ready to go is 9050 pounds. GVWR of the truck is what? 11,000 pounds? 11,000 minus 9050, OK round it to 9000 equals 2000 pounds. That is how much pin weight you can carry before exceeding the trucks GVWR if you calculate pin weight at the accepted 20%, then you can safely hitch up to a 10,000 fiver. Im guessing that is really consertarive as most folks with 350/3500 SRW series trucks are pulling 13-14K fivers with no problems. You need to understand that what the factory claims their truck can pull is assumed pulling a flat bed trailer, not a high walled sail. So take their numbers with a grain of salt! If we assume yo1ur loaded truck including hitch at 9000,look on the drivers door post for the MFG GVWR number, subtract B from A and you have your answer.