I think the early sump screens were 1-7/16 and the later ones were 1-1/2. There's a guy on eBay who sells a nice heavy multi-tool that fits the sump, tightens exhaust collars, and has drivers for the primary inspection caps all in one. The sump hex fits my brother's 750 but not my 850.
I have a Craftsman 1-1/2 that I bought for the main sprocket nut and it set me back $30. One big azz wrench.