How long can you safely cure using Morton's Tender Quick? Morton's Tender Quick says to cure for hours, but the curing recipe I am using says to cure my ham for 4 days. I am wondering does Morton's Tender Quick cure so fast that it only needs hours? Or can I cure with it as long as 4 days? or is that only for insta-cure and pink salt? 

I am way confused. I can only find Morton's and I really just want to get started curing.
Morton's Tender Quick is a fast cure salt meant to be mixed in with ground meats or used for curing thinner cuts (or fish). Hams must be brined for days in order for the salt solution to penetrate deeply through the flesh and prevent spoilage. It is important to follow good curing protocol and use the amount of salt as requested in the recipe.

Sodium nitrate, or pink salt #2, is not essential from a food safety perspective for whole muscle curing but is for dry-curing various salumi.