Trans pan gasket..sealer or no sealer?? and other trans ???

I'll throw my $.02 worth in too.....Hammer the pan rail flat around the bolt holes, clean it off real good, put a light coat of CopperCoat sealer between the pan and gasket and nothing between the gasket and case. This is what I do with a conventional cork or paper gasket. If it's the rubber/reusable ones, no sealer at all. Just about any ATF will work (except type A) but since they're all about the same price, use the latest and greatest Dexron or ATF+4 for their added properties. As fishy68 said, an auto trans squeal is virtually unheard of. If it makes that noise just sitting still, take off all the belts and fire it up for a few seconds. If it's quiet now, it's something driven by a belt. Spin those items by hand or start adding belts back on until you find the culprit.