Where is the transmission oil drain plug on a 1989 Harley Davidson heritage?

I believe it is on the bottom of the transmission. You should be able to see it. If you are going to preform your own service, it is well worth the cost to purchase a repair manual. You can usually find one cheap on eBay or other internet sites.

the tranny drain plug should be behind the front muffler, I think it takes an Allen wrench to remove it