Alldata says 7 hrs to R&R, we have done so many here it takes maybe 5 hrs. I put a jack and 4x4 block between the frame and spread it so the cross member comes out easier and I have lifts and a nice trans jack. About 16HRs total to rebuild and R&R depednding on skid plate add ons and such. If I am rebuilding a customers trans it takes a couple days. I give a basic re-build estimate with clutches seals... and tell them if there is hard part damage it is extra depending on the part. I prefer to build one from my cores first so we can swap it in a day and the truck is not tore down holding up a lift for a 2-3 days, if the customer lets me do it this way there is no hard part charges. I usually keep 20 or so cores around so I always have what I need, I buy them off CL or local yards when they let me have em cheap. Just one of my many tricks for keeping costs to the customer low.

John is right about the fluid, it does also protect the bearings and gears, however in my experiance there is waaaay more clutch/band burning problems so I lean toward protecting them.