Use no sealer as it tends to allow the gasket itself to squeeze out. Make sure the bolt holes in the pan are flat and the pan and trans case are scraped clean. Use a solvent to get all the oil off the surfaces. You can use a high tack to hold the gasket in pace but I usually put a couple of bolts through the pan and gasket and thread them
Overview. OEM specified. Formulated specifically for metal, tapered pipe thread fittings, it replaces thread seal tape and pipe dopes. Cures rapidly to withstand 10,000 PSI. Prevents galling and protects mated threaded areas from rust and corrosion. Contains PTFE.