I have a 1987 D250, 318 HD 4speed manual trans. NOT an 833 trans. I forget the model # of the one that's in it, but there are 2 clutch kits available for it from Rock Auto, an 11" & 10 1/2". I'm thinking mine is 11" & the 833 trans. are 10 1/2", but not sure. I don't want to disable the truck just to measure the disc that's in it, if I don't have to. Does anyone know off hand what size clutch kit I need?