Expensive compared to other seals, but very good seal. I installed this on my 98 F150 (4.6 litre, 8.8 rear gear) and couldn't be happier with the result. If upon installation the surface of your body is clean and there are no large grooves, and if your cover is not bent or has indentations on the flange surface, then sealant is not required. After reworking the rear a little, I made sure the crankcase finish was clean and tidy and installed a gasket with a new cover (it's pretty cheap, I highly