My Cub Cadet 3185 developed a leak where the differential mates to the axle plate. I bought new CC gaskets and the factory service manual that specs Loctite 5999. It was not available locally, so NAPA suggested Permatex Ultra Blue gasket maker. It didn't work, still leaked in the same spot. Followed all directions.

So... after more research and talking with the NAPA people, I used Permatex Ultra Copper, with no gasket at all. Waited probably 45 minutes in the 40 degree garage for it to skin over, and torqued the fasteners to 30 in lbs, finished them to 90 in the morning in several steps. No problems at all. A fantastic product.

One side note, I couldn't easily separate the rear pan from the axle plate, so I left it in-place with factory gasket and the Ultra Blue and it is working fine.