8 3/4 Help and Opinions?

I'm in the same boat as you Haney. Mine also has the 7260's and I'm thinking about upgrading to 7290's. With your 340 and 4 spd and street tires it's not quite as much concern but if you go up to that stroker I'd sure be affraid those 7260's wouldn't survive long. As far as I know no 8-3/4 came from the factory with a solid sleeve. Those were aftermarket only but someone could have put one in yours. That being the case if it don't have it you take the risk of messing up the pinion depth by swapping the yoke.